Alert Codes and Troubleshooting Critical Alerts Are Displayed on the Home Screen, in the Homeowner Alert Button, and in the Installer Alert Button

Homeowner Service Alert Codes

Number Value Number Value Number Value Number Value Number Value 3000 Filter 1 3002 Humidifier Pad 3004 Maintenance 4000 User Wi-Fi state change, 4002 Image file download disable failed 3001 Filter 2 3003 UV Light 3005 PureAir 4001 Firmware download failed Maintenance

Comfort Sync® Alert Codes and Troubleshooting Critical alerts are displayed on the Home screen, in the Homeowner alert button, and in the Installer alert button. Minor and moderate alerts are found only in the Installer alert button.

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code 10 Critical Thermostat, air The thermostat has found an Clear alert code by handler, furnace, unknown device on the system. • The room thermostat when not in reconfiguring the outdoor unit, configuration mode has detected an system. equipment unknown device. interface and • Typically the thermostat will send a damper control command to the unknown device modules. and place it in a soft disable state. • The Comfort Sync® control with the soft disable state will indicate so as follows: > On air handler, furnace and outdoor controls, the state is display by double horizontal lines on seven-segment display. > On the damper control module, the green LED will blink 3 seconds on and 1 second off. > On the equipment interface

1 Comfort Sync 7-Day Programmable Communicating Thermostat

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code module, the green LED will blink 3 seconds on and 1 second off. • Cycling power to the soft disable controller may clear the condition. If cycling power does not clear the soft disable state then replace control. 11 Critical The thermostat cannot find a If problem persists, Thermostat Check all connections and cycle previously installed system • clear by reconfiguring component. system power. the system • Press the setup tab, press start, and press confirm. • If problem persists, then check all system components (devices) connections to make sure they are Comfort Sync®-compatible. 12 Critical The thermostat cannot find a Automatically clears Thermostat, • Thermostat did not find an indoor furnace, Comfort Sync® indoor unit. when the system unit. Make sure there is a Comfort equipment detects that the issue Sync® indoor unit on the system. interface module no longer exists. Check R, i+, i- and C connections. or air handler • Ohm wires and cycle power. • Replace indoor unit control if there is no response. 14 Critical The thermostat found more than Automatically clears Thermostat Check wiring and remove duplicate one thermostat, indoor or • when the system outdoor unit on the system. equipment. detects that the issue • Reconfigure system. no longer exists. 18 Minor The outside temperature is This is a notification Thermostat The system will not use the heat below the level where the heat • only alert code. pump is programmed to heat the pump to warm your home. home. • Outdoor temperature is below the low balance point. 2

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code • Heat pump will not be used to service a heating demand. 19 Minor The outside temperature is Automatically clears Thermostat The system will only use the heat higher than the level where the • when the system furnace or electric heat is pump to warm your home detects that the issue programmed to work. • This is a notification only alert code. no longer exists. • Outdoor temperature is above the low balance point. • Indoor unit (furnace or air handler) will not be used to service a heating demand. 29 Critical The thermostat is reading an Automatically clears Thermostat Indoor temperature rose above indoor temperature that is higher • when the system than 99ºF. The thermostat will 99ºF during a heating or cooling detects that the issue not allow any heating operation demand. no longer exists. to begin until it senses an indoor • Heating operation is not allowed. temperature lower than 99ºF. • Check to ensure that heating equipment is not stuck ON (reversing valve, etc.). • Check the accuracy of the thermostat temperature sensor. • Select cooling system mode to cool the indoor space. 30 Moderate The thermostat is reading an Automatically clears Thermostat The thermostat will not allow any indoor temperature that is lower • when the system than 40ºF. cooling operation to begin until it detects that the issue senses a temperature higher than no longer exists. 40ºF. • Indoor temperature fell below 40ºF. • Cooling operation is not allowed. • Check to ensure that cooling

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Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code equipment is not stuck ON. • Check accuracy of the thermostat temperature sensor. • Select heating system mode to heat the indoor space to above 40ºF. 31 Critical The thermostat has lost Thermostat The applicable system component If fault persists, then communication with a system • • component for more than three (indoor, equipment interface or cycle power. damper control module or outdoor minutes. Fault clears after unit) has not communicated with • thermostat for more than three communication is minutes. restored. • Check connections. • Ohm wires. 32 Moderate The applicable system This alert code is Thermostat, • This issue may occur during a furnace, air component (device) is resetting cleared by pressing power outage or power fluctuation handler or itself. the clear button on in the system. outdoor unit the Installer Alerts • If persistent or if it coincides with the Tab. system operations then proceed with the following troubleshooting steps. > Check the power connections > Check the amp draw at the transformer (the transformer maybe overloaded) > Check 24VAC voltage at the system component (device). • If the fault persists after checking the connections, replace the unit's control board. 4

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code 34 Critical The thermostat does not know Automatically clears Thermostat The applicable system component the capacity (tonnage) of the • when the system indoor or outdoor unit. is missing the programmed unit detects that the issue capacity. no longer exists. • Go to applicable system component and program the unit capacity manually (see the unit installation instruction for programming instructions). • Remove power to thermostat before programming the unit control. • Once programming is complete, reconnect thermostat wires and reconfigure system. 36 Critical The system has been heating for Automatically clears Thermostat • Run the system in diagnostic mode at least 15 minutes without a when the system and verify that it matches actual demand for heating. detects that the issue equipment operation. no longer exists. • Check for other alert codes that may be preventing the system from operating as expected. • Check all heating equipment to determine cause of heating demand. • Recycle power. 37 Critical The system has been cooling for Automatically clears Thermostat Run the system in diagnostic mode at least 15 minutes, without a • when the system demand for cooling. and verify that it matches actual detects that the issue equipment operation. no longer exists. • Check for other alert codes that may be preventing the system from operating as expected. • Check all cooling equipment to

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Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code determine cause of cooling demand. • Recycle power. 38 Critical The system has not been able to Automatically clears Thermostat • The system will go offline for 60 turn on the heating for more than when the system 45 minutes. minutes and will attempt to restart detects that the issue itself. no longer exists. • Run the system in diagnostic mode and verify that it matches actual equipment operation. • Check for other alert codes that may be preventing the system from operating as expected. • Check all heating equipment to determine cause. • Recycle power. 39 Critical The system has not been able to This alert code will Thermostat The system will go offline for 60 turn on the cooling for more than • automatically clear 45 minutes. minutes and will attempt to restart when the system itself. detects the issue has • Run the system in diagnostic mode no longer exists. and verify that it matches actual equipment operation. • Check for other alarms/codes that may be preventing the system from operating as expected. • Check all cooling equipment to determine cause. • Recycle power. 40 Minor Outdoor Unit • The HP could not progress the • The heat pump has locks out on the • Clears when heat room temperature 0.5°F "HP heating Lockout Time" setting pump comes out of towards the set point in 30 in the room thermostat "HP heating Lockout 6

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code minutes. "Installer/System Devices / Heat Time" timer setting Pump screen" (Default is 120 (Range can be set System will switch to secondary • minutes). The issue is the heat between 60 to 120 heat source. pump could not progress the room minutes. temperature by 0.5F towards the • (Secondary source is electric • Default is 120 heat or furnace in dual -fuel set point in 30 minute. minutes). applications). • Set the low balance point and high • (Software issue: The issue is balance point as close together as the 30-minute timer is not possible. (This is 3°F difference – resetting to 30 minutes when Example: set high balance point at the temperature raises 0.5°F. 35°F and low balance point would set at 32F). • After 30 minutes, it causes alarm 40 to be set • Below the low balance point, the (erroneously), and the heat furnace will heat the home / pump goes into the “HP heating between the low and high balance Lockout Time” mode which point, the heat pump and furnace indicates that the heat pump will heat the home. could be off for a maximum of • If the heat pump cannot raise the 120 minutes. Range can be set temperature 0.5°F in 30 minutes on between 60 to 120 minutes) the zone or zones, the “HP heating Lockout Time” (Location: Installer set/System devices/HP heating Lockout Time / default is 120 minutes) will lock the heat pump off. • The gas furnace will finish the heating cycle / when the outdoor temperature is above the high balance point. • The gas furnace is locked out and all the heat is provided by the heat pump. 105 Critical A system component has lost Automatically clears Thermostat, • System component (device) is furnace, air communication with the system. when the system unable to communicate. handler, outdoor detects the issue no

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Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code unit, equipment longer exists. This may indicate the existence of interface or • damper control other active alert codes. module • In most cases errors are related to electrical noise. Verify that high voltage power is separated from the low voltage communication wires. • Check for incorrectly wired or loose connections between system components (devices). • Check for a high voltage source of noise close to the system. 110 Critical The component line voltage is Automatically clears Furnace This alert code may appear during a too low. • when the system brownout. detects the issue no • Line voltage is below its designed longer exists. operating value. • Check and correct the power line voltage. 111 Critical The component line power Automatically clears Furnace The unit is reporting that its power voltage wiring is reversed. • when the system and neutral lines are reversed. detects the issue no • Turn off the power to the system longer exists. and correct the line power voltage wiring. • System resumes normal operation five seconds after critical condition is recovered. 112 Critical The reporting component cannot Automatically clears Furnace The thermostat will shut down the find earth ground. • when the system system. detects the issue no • Provide proper earth ground to the longer exists. equipment.

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code • System resumes normal operation five seconds after critical condition is recovered. 113 Critical The line voltage is too high. Automatically clears Furnace Line voltage high (voltage higher • when the system than nameplate rating). detects the issue no • Provide power voltage within proper longer exists. range. • System resumes normal operation five seconds after critical condition is recovered. 114 Moderate / There is a frequency / distortion Automatically clears Furnace, air • This alert code may indicate Critical handler, problem with the power to a when the system transformer overloading. equipment specific system component. detects the issue no interface or • Check the voltage and line power longer exists. damper control frequency. module • Check the generator operating frequency, if the system is running on back-up power. • Correct voltage and frequency problems. • System will resume normal operation five seconds after fault recovered. • All applicable system component outputs are disabled – moderate condition. • After 10 minutes, the priority condition is escalated – critical condition. • Damper control module will operate in central mode only until proper

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Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code voltage is restored or frequency distortion is resolved – moderate condition. 115 Critical Primary 24VAC power to a Automatically clears Furnace, air • Primary 24VAC voltage is low handler or system component control is when the system (range is 18 to 30 volts). equipment lower than the required range of detects the issue no interface module 18 to 30VAC. • Check and correct voltage. longer exists. • Check for additional power-robbing system component (device) connected to system. • This alert code may require the installation of an additional or larger VA transformer. 115 Critical Secondary 24VAC power to the Automatically clears Damper control • Secondary 24VAC voltage is low module damper control module is low. when the system (range is 18 to 30 volts). detects the issue no • Check and correct voltage. longer exists. • Check for additional power-robbing equipment connected to system. • This alert code may require the installation of an additional or larger VA transformer. • Damper control module will operate in non-zone mode until proper voltage is restored. 117 Minor The reporting unit has poor earth Automatically clears Furnace Provide proper grounding for the grounding. • 30 seconds after the system component (device). issue is corrected. • Check for proper earth ground to the system. 120 Moderate There is a delay in the system Automatically clears Thermostat, • Typically this alert code does not furnace, air component responding to the after an unresponsive cause any operational issues and handler, outdoor system. system component 10

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code unit, equipment will clear on its own. (device) responds to interface or any inquiry. This alert code is usually caused by damper control • module a delay in the outdoor unit responding to the thermostat. • Check all wiring connections. 124 Critical The thermostat has lost Automatically clears Thermostat, • System component has lost furnace, air communication with a system after communication communication with the thermostat. handler, outdoor component for more than three is re-established with unit, equipment minutes. • Check the wiring connections. applicable system interface or component (device). Ohm wires. damper control • module • Cycle power. • This alert code stops all associated system operations and waits for a heartbeat message from the system component that is not communicating. 125 Critical There is a hardware problem on Automatically clears Thermostat, • There is a control hardware furnace, air a system component control. 300 seconds after the problem. handler, outdoor issue no longer unit, equipment • Replace the control if the problem exists. interface or prevents operation and is damper control persistent. module • Damper control module will remain in non-zone mode (all dampers open) for five minutes after priority condition no longer exist. 126 Critical There is an internal Automatically clears Furnace air • There is an internal hardware handler or communication problem with a 300 seconds after the problem on the system component outdoor unit system component. issue no longer control. exists. • Typically the system component control will reset itself.

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Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code • Replace the system component (device) control if the problem prevents operation and is persistent. 130 Moderate Air handler jumper is missing. Automatically clears Equipment • Configuration jumper missing on interface module after the missing or equipment interface module. incorrectly installed NOTE: This is applicable in jumper is installed or non-communicating applications corrected. only). • Install the missing jumper. 131 Critical System component control Will automatically Thermostat, • Reconfigure the system. furnace, air parameters are corrupted. clear when system handler, outdoor • Replace the system component component (device) unit, equipment control if heating or cooling is not passes memory interface or available. self-test or system damper control component control is module replaced. 132 Critical System component control Manual system Air handler, • Recycle power. equipment software is corrupted. power reset is interface module • If failure re-occurs, replace the required to recover or damper control system component control. from this alert code. module 180 Critical The thermostat has found a Automatically clears Furnace, air • In normal operation after system handler or problem with a system upon configuration, or component control recognizes equipment component's outdoor sensing normal sensors, the alarm will be sent if interface module temperature sensor. values. valid temperature reading is lost. • Compare outdoor sensor resistance to temperature / resistance charts in unit installation instructions. • Replace sensor pack if necessary. • At the beginning of (any) configuration, furnace, air-handler

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code control or equipment interface module will detect the presence of the sensor(s). • If detected (reading in range), appropriate feature will be set as 'installed' and shown in the 'About' screen. 200 Critical The furnace roll out limit switch Automatically clears Furnace Correct the cause of roll out trip. is open. • after the furnace roll • Reset roll out switch. out switch is closed. • Test the furnace operation. 201 Critical The system has lost Automatically clears Furnace or air • Lost communication with indoor handler communication with the indoor after communication unit's blower motor. blower motor. is restored. • Possible causes include power outage, brown-out, motor not powered, loose wiring, condensation on system component control without cover on breaker. • Problem may be on system component control or motor side. 202 Critical The unit size code for the indoor Automatically clears Furnace or air • Incorrect appliance unit size code handler unit and the size of blower motor after the correct do not match. selected. match is detected • Check for proper configuring under following a reset. unit size codes for furnace/air handler on configuration guide or in installation instructions. • Remove the thermostat from the system while applying power and reprogramming. 203 Critical The unit size code for the indoor Automatically clears Furnace or air • No system component unit size after the correct

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Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code handler unit has not been selected. code selected. match is detected following a reset. • Check for correct configuration. Unit size codes for furnace and air handler are listed in the system component configuration guide or installation instruction. • Remove the thermostat from the system while applying power and reprogramming. 204 Critical There is an issue with the Automatically clears Furnace Check gas valve operation and furnace gas valve. • after the issue is wiring. corrected. 205 Critical Furnace The furnace gas valve relay Check wiring on control and gas valve. Automatically clears contact is closed. after the issue is corrected. 206 Critical The furnace gas valve Automatically clears Furnace Furnace will operate on first-stage second-stage relay is faulty. • after the issue is for the remainder of the heating corrected. demand • If unable to operate second-stage, replace furnace control. 207 Critical The furnace hot surface igniter is Automatically clears Furnace Measure the resistance of hot open. • after the issue is surface igniter. corrected. • Replace the igniter if it is not within the specified range found in furnace installation instruction. 223 Critical The furnace low pressure switch Automatically clears Furnace Check pressure (inches w. c.) of the is open. • after the issue is low pressure switch closing during a corrected. heat call. • Measure operating pressure (inches w. c.). • Inspect vent and combustion air 14

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code inducer for correct operation and restriction. 224 Critical The furnace low pressure switch Automatically clears Furnace Check operation of low pressure is stuck closed. • after the issue is switch to see if it is stuck closed for corrected. longer than 150 seconds during a heat call. • Measure operating pressure (inches w. c.). • Inspect vent and combustion air inducer for correct operation and restriction. 225 Critical The furnace high pressure Automatically clears Furnace Check pressure (inches w. c.) of switch is failing to close. • after the issue is high pressure switch closing during corrected. a heat call. • Measure operating pressure (inches w. c.). • Inspect vent and combustion air inducer for correct operation and restriction. 226 Critical The furnace high pressure Automatically clears Furnace Check operation of high pressure switch is stuck closed. • after the issue is switch closing during a heat call. corrected. • Measure operating pressure (inches w. c.). • Inspect vent and combustion air inducer for correct operation and restriction. 227 Moderate The furnace low pressure switch Automatically clears Furnace Check pressure (inches w. c.) of low is open in run mode. • after the issue is pressure switch closing during a corrected. heat call. • Measure operating pressure

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Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code (inches w.c.). • Inspect vent and combustion air inducer for correct operation and restriction. 228 Moderate The furnace control is not able to Automatically clears Furnace Unable to perform pressure switch calibrate the pressure switch. • after a successful calibration. calibration. • Check vent system and pressure switch wiring connections. • Check the drain trap for blockage. 229 Minor Furnace The furnace control has Furnace control switched to high fire No action is needed. switched to high fire ignition ignition because low fire pressure because the low fire pressure switch did not close in allowed time. switch did not close in the allowed time. 240 Moderate The furnace flame current is low. Automatically clears Furnace Check micro-amperes of the flame • after a proper sensor using thermostat micro-amp reading diagnostics. has been sensed. • Clean or replace the flame sensor. • Measure voltage of neutral to ground to ensure good unit ground. 241 Critical The furnace flame is going out Automatically clears Furnace Shut off gas. while the furnace is heating. • when a heat call ends • Check for a gas valve leak. successfully. • Replace the gas valve if needed. 250 Moderate The furnace primary limit switch Automatically clears Furnace Check for proper firing rate on is open. • when a heat call ends furnace. successfully. • Ensure there is no blockage in the furnace and the duct work. • Check for proper air flow.

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code • If limit switch is not closed within three minutes, the unit will go into one hour WatchGuard mode. 252 Moderate The furnace discharge Automatically clears Furnace Check temperature rise, air flow air-temperature is high. • when a heat call ends and input rate. successfully. • Check for dirty air filter(s). . 270 Critical The furnace is in WatchGuard Automatically clears Furnace This is a five strike condition during mode. The furnace igniter • on successful cannot turn on the flame. a single demand. ignition. • Check for proper gas flow. • Ensure that igniter is lighting burner. • Check flame sensor current. • Check for dirty filters. 271 Critical The furnace is in WatchGuard Automatically clears Furnace This is a five strike condition during mode. The furnace low pressure • on successful switch is open. a single demand. ignition. • Check pressure (inches w. c.) of low pressure switch closing during a heat call. • Measure operating pressure (inches w. c.). • Inspect vent and combustion air inducer for correct operation and restriction. 272 Critical The furnace low pressure switch Automatically clears Furnace The system will go into WatchGuard is open during run mode. • when a heat call ends mode. successfully. • Check operation of low pressure switch to see if it is stuck open during a heat call. • Measure operating pressure

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Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code (inches w. c.). • Inspect vent and combustion air inducer for correct operation and restriction. 273 Critical The furnace flame is going off Automatically clears Furnace The system will go into WatchGuard during a heating cycle. • when a heat call ends mode. successfully. • Check micro-amperes of flame sensor using thermostat diagnostics. • Clean or replace sensor. • Measure voltage of neutral to ground to ensure good unit ground. . 274 Critical The furnace limit switch has Automatically clears Furnace • The system will go into WatchGuard been open for more than three when a heat call ends minutes. mode. successfully. • Check firing rate and air flow. • Check for blockage. 275 Critical The furnace flame is out of Automatically clears Furnace The system will go into WatchGuard sequence. • on successful mode. ignition. • Shut off gas. • Check for gas valve leak. 276 Critical The furnace is not able to Automatically clears Furnace The system will go into WatchGuard calibrate or the high pressure • when the furnace switch opened or failed to close mode. calibrates itself in run mode. • Check vent system and pressure successfully. switch wiring connections. 290 Critical There is a problem with the Automatically clears Furnace The system will go into WatchGuard furnace ignition circuit. • on successful ignition mode.

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code • Measure resistance of hot surface igniter. • Replace the hot surface igniter it is not within specifications. 291 Critical The heating airflow is below the Automatically clears Furnace The system will go into WatchGuard minimum required level. • when a heat call ends mode. successfully. • Check for dirty air filter(s) and other air flow restrictions. • Check blower performance. 292 Critical The indoor unit blower motor will Automatically clears Furnace or air • The system will go into WatchGuard handler not start. after the indoor mode. blower motor starts • Indoor blower motor unable to start. successfully. • This could be due to seized bearing, stuck wheel, and obstructions. • Replace motor or wheel if assembly does not operate or meet performance standards. 294 Critical There is over current in the Automatically clears Furnace The system will go into WatchGuard furnace inducer motor. • after inducer motor mode. current is sensed to • Check combustion blower bearings, be in-range after the wiring and amps. ignition following either WatchGuard • Replace furnace inducer motor if it mode or unit reset. does not operate or does not meet performance standards. 295 Minor The indoor blower motor is Automatically clears Furnace Indoor blower motor over overheating. • after blower demand temperature (motor tripped on is satisfied. internal protector). • Check motor bearings and amps.

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Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code • Replace indoor blower motor if necessary. 310 Moderate There is a discharge air Automatically clears Furnace, air • Compare outdoor discharge sensor handler temperature sensor issue. 30 seconds after fault resistance to temperature / equipment is detected as resistance charts in system interface module recovered or after component installation instruction. or damper control system power reset. module • Replace discharge air sensor if necessary. • iHarmony will operate in non-zone mode (all dampers open). NOTE: Confirm there is no short or open circuits in the Comfort Sync® thermostat connections to any of the other components in the communication system. 311 Minor The heat firing rate has been Automatically clears Furnace This is a Warning Only alert code. reduced to match available • when a heat call airflow (cutback mode). • Furnace blower in cutback mode finishes successfully. due to restricted airflow. • Reduce firing rate every 60 seconds to match available CFM. • Check air filter and duct system. • To clear, replace air filter if needed or repair or add additional ducting. • Two-stage controls will reduce firing rate to first stage. 312 Minor The indoor blower cannot Automatically clears Furnace or air • This is a Warning Only alert code. handler provide the requested CFM due after the current to high static pressure. • Possible restricted airflow - Indoor service demand is blower is running at a reduced CFM satisfied. (Cutback Mode).

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code • The variable speed motor has pre-set speed and torque limiters to protect the motor from damage caused by operating outside of design parameters (0 to 0.8” e.g. total external static pressure). • Check air filter and duct system. • To clear, replace air filter if needed or repair or add additional ducting. 313 Minor The indoor and outdoor unit Automatically clears Furnace, air • This is a Warning Only alert code. handler and capacities do not match. after commissioning outdoor unit • Check for proper system is complete. component configuring in installation instructions. • The system will operate, but might not meet efficiency and capacity parameters. 344 Critical Furnace Relay Y1 Failure • Possible Y1 relay failure. Automatically clears 300 seconds • All system operations will stop. after Y1 input sensed OFF. 345 Critical The O relay on the system Automatically clears Air handler, • Possible O relay / stage 1 failure. equipment component has failed. Either the after the fault interface module pilot relay contacts did not close • Pilot relay contacts did not close or recovered following or heat pump or the relay coil did not energize. the relay coil did not energize. reset. • Replace system component (device) control. • If error is applicable to the XC/XP 25, the outdoor control will need to be replaced. 346 Critical The heat pump configuration link Automatically clears Air handler • Configuration link not cut on air not cut on the air handler control. when the system

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Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code handler control. detects that the issue no longer exists. • Cut O to R. • This is only applicable with non-communicating heat pump with communicating indoor unit. 347 Critical The Y1 relay on the applicable Automatically clears Furnace, air • System operation will stop. handler or system component has failed. after reset and Y1 equipment Either the pilot relay contacts did • Possible Y1 relay / stage 1 failure. input sensed. interface module not close or the relay coil did not energize. • Pilot relay contacts did not close or the relay coil did not energize; • There is no input back to the applicable system component control. 348 Critical The Y2 relay on the applicable Automatically clears Furnace or air • Possible Y2 relay / stage 2 failure. handler system component has failed. when the system Either the pilot relay contacts did • Furnace pilot relay contacts did not detects that the issue not close or the relay coil did not close or the relay coil did not no longer exists. energize. energize • No input back to furnace or air handler control. . 349 Critical The O to R link on the furnace Automatically clears Furnace • Configuration link R to O needs to needs to be restored. when the system be restored. detects that the issue • Repair cut link or hard-wire. no longer exists. • Only applicable in non-communicating mode. 350 Critical The air-handler's electric heat is Automatically clears Air handler Heat call with no configured or not configured or incorrectly • after electrical heat configured. incorrectly configured electric heat. detection is • Check for proper configuring under successful. Configuring Electric Heat Stages in the air handler installation

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code instructions. 351 Critical There is an issue with the Automatically clears Air handler Either the pilot relay contacts did air-handler's first stage electric • after fault recovered. heat. not close or the relay coil in the electric heat section did not energize. • Possible heat section / stage 1 failure. • Pilot relay contacts did not close, or the relay coil in the electric heat section did not energize. • Air handler will operate on first stage for reminder of the heat call. 352 Critical There is a problem with the Automatically clears Air handler Either the pilot relay contacts did air-handler's second stage • after fault recovered. electric heat. not close or the relay coil in the electric heat section did not energize. • The air-handler will operate on first stage electric heat until the issue is resolved. 353 Critical There is a problem with the Automatically clears Air handler Either the pilot relay contacts did air-handler's third stage electric • after fault recovered. heat. not close or the relay coil in the electric heat section did not energize. • The air-handler will operate on first stage electric heat until the issue is resolved. 354 Critical There is a problem with the Automatically clears Air handler Either the pilot relay contacts did air-handler's fourth stage electric • after fault recovered. heat. not close or the relay coil in the electric heat section did not energize. • The air-handler will operate on first

23 Comfort Sync 7-Day Programmable Communicating Thermostat

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code stage electric heat until the issue is resolved. 355 Critical There is an issue with the Automatically clears Air handler Either the pilot relay contacts did air-handler's fifth stage electric • after fault recovered. heat. not close or the relay coil in the electric heat section did not energize. • The air-handler will operate on first stage electric heat until the issue is resolved. 370 Critical Furnace The furnace control has not This alert code will The system will not operate. received 24VAC power for two • clear when 24VAC is minutes or more on the DS • Dealer has cut the W914 jumper continuously sensed terminal (Dehum, Harmony III) on DS terminal for a minimum of 10 • The thermostat monitors the DS seconds or on a terminal in the furnace for power power reset. and if the link has been cut then power will be lost to DS. 380 Moderate / Interlock relay failure (IFC or Automatically clears Equipment • Interlock relay is energized, but Critical interface module AHC mode only). after fault recovered. input is not sensed after three seconds. • There will be no heating or cooling due to this alert code – moderate condition. • De-energize interlock relay and energize after five minutes if demand is still present – critical condition. 381 Moderate / Interlock relay stuck (IFC or Automatically clears Equipment • Interlock relay continuously sensed Critical interface module AHC modes only) 30 seconds after fault (with relay off). clears. • There is no heating and cooling operation – moderation condition.

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code • After 10 minutes if event still exist it will be escalated – critical condition. 382 Moderate Equipment Relay W1 failure (IFC and AHC W1 relay is energized but input is not Automatically clears interface module modes only) sensed after three seconds. when W1 relay input is sensed. 400 Critical The compressor internal Automatically clears Outdoor unit • Thermostat demand Y1 is present; overload has tripped. when the system however compressor is not running. detects that the issue • Check power to unit. no longer exists. • This alert code is automatically cleared after current is sensed in both RUN and START sensors for at least two seconds or after service is removed, or after power reset. 401 Moderate Either the compressor ran for Automatically clears Outdoor unit • Alert code will not lockout system. more than 18 hours continuously after 30 consecutive trying to cool the home during a • If the two-stage outdoor unit has: normal run cycles or single demand or the refrigerant power reset. pressure in the system is low. • An outdoor control with blinking LED lights then the unit will run in low speed; • An outdoor control with a 7-segment display, the outdoor control will display alert code 401, but continue to run in high speed. • If the outdoor unit is a heat pump, and the outdoor temperature is less than 65°F, alert code 401 is ignored. • Also monitors low pressure switch trips. 402 Critical Outdoor unit Either the discharge or suction Check discharge or suction pressure. Automatically clears pressure level is out-of-limits, or after four consecutive

25 Comfort Sync 7-Day Programmable Communicating Thermostat

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code the compressor has overloaded. normal compressor run cycles. 403 Moderate The compressor ran for less Automatically clears Outdoor unit This short cycle fault is triggered than three minutes to satisfy a • after four consecutive thermostat demand. when five compressor cycles lasted normal compressor less than four minutes. The run cycles. compressor cycles could have ended for any reason, thermostat NOTE: Code removed from satisfied or high-pressure switch for example. outdoor control - Part # 103369-03 and later / Cat # 11H36 Kit). 404 Critical The compressor rotor is locked Automatically clears Outdoor unit Compressor rotor locked up due to up. • after four consecutive run capacitor short, normal run cycles or • Bearings are seized after power reset. • Excessive liquid refrigerant, etc. (NOTE: May need to install hard start kit). 405 Critical Outdoor Unit The compressor circuit is open. Compressor circuit open (due to power Automatically clears disconnection - open fuse, etc.) after one normal compressor run cycle. 406 Critical The required amount of current Automatically clears Outdoor unit • The start current sensors look for is not passing through the after current is the presence of a minimum of three START current transformer. sensed in START amps current (for up to 15 seconds) sensor, or after power on the run and start windings of the reset. compressor while there is a Y1 signal. If no current is sensed with the Y1 signal still present, the control will cycle the Y1 demand, which will cycle compressor OFF. • Check wiring at outdoor control and compressor amperage.

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code • NOTE: This alert code is applicable only to first-generation outdoor unit that had current sensors. 407 Critical The required amount of current Automatically clears Outdoor unit The start current sensors look for is not passing through RUN • after current is current transformer. the presence of a minimum of three sensed in RUN amps current (for up to 15 seconds) sensor, one normal on the run and start windings of the compressor run compressor while there is a Y1 cycle, or after power signal. If no current is sensed with reset the Y1 signal still present, the control will cycle the Y1 demand, which will cycle compressor OFF. • Check wiring at outdoor control and compressor amperage. • NOTE: This alert code is applicable only to first-generation outdoor unit that had current sensors. 408 Critical The compressor is running Automatically clears Outdoor unit Welded contacts continuously. • after one normal • Replace compressor contactor. compressor run cycle or after power reset. • Confirm 24VAC power to contactor. • Verify all wiring connections are tight to contactor terminals. 409 Moderate The secondary voltage for the Automatically clears Furnace, air • Secondary voltage is below 18VAC. handler or applicable system component after voltage is outdoor unit has fallen below 18VAC. • If this continues for 10 minutes, the detected as higher thermostat will turn off the than 20VAC for two applicable system component. seconds or after power reset. 410 Moderate Unit low pressure is below the Automatically clears Outdoor unit Check operating pressures. required limit. • when the system • Low pressure switch opens at 40 detects that the issue psig (system shuts down) and no longer exists.

27 Comfort Sync 7-Day Programmable Communicating Thermostat

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code closes at 90 psig (system restarts). 411 Critical The low-pressure switch has Automatically clears Outdoor unit Thermostat will shut down the opened five times during a • when the system single demand. outdoor unit. detects that the issue • Open low pressure switch error no longer exists. count reached five strikes. • Check system charge using approach and sub cooling temperatures. • Reset by putting outdoor unit control in test mode or resetting low voltage power. 412 Moderate The unit high-pressure is above Automatically clears Outdoor unit System is shut down the required limit. • after the high • Unit high pressure is above the pressure switch upper limit. closes or a power reset • The high pressure switch for HFC•410A will open at 590PSIG and close at 418PSIG. • Confirm that the system is properly charged with refrigerant. • Check outdoor fan motor, TXV, indoor unit blower motor, stuck reversing valve and possible clogged refrigerant filter. • Confirm that the outdoor unit is clean. 413 Critical The high-pressure switch has Automatically clears Outdoor unit Thermostat will shut down the opened five times during a • when the system single demand. outdoor unit. detects that the issue • Open high pressure switch error no longer exists. count reached five strikes.

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code • Check system charge using approach and sub cooling temperatures. • Check outdoor fan operation. • Check for dirt or debris blocking air flow to outdoor unit. • Reset by putting outdoor unit control in test mode or resetting low voltage power. 414 Critical The discharge line temperature Automatically clears Outdoor unit Discharge line temperature is is higher than the recommended • after discharge upper limit of 279ºF. greater than 279ºF. temperature is less • Make sure coil is clean and airflow than 225ºF. unobstructed in and out of condenser. • Check system operating pressures and compare to unit charging charts in installation manual. 415 Critical The discharge line temperature Automatically clears Outdoor unit Discharge line high temperature has been consistently higher • when the system than the recommended upper error count reached five strikes detects that the issue limit of 279ºF. during a single demand. no longer exists. • Make sure coil is clean and airflow unobstructed in and out of condenser. • Check system charge using approach and sub cooling temperatures. • Reset by putting outdoor control in test mode or resetting low voltage power. 416 Critical The outdoor coil sensor is either Automatically clears Outdoor unit • Outdoor unit control will not perform

29 Comfort Sync 7-Day Programmable Communicating Thermostat

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code open, short-circuited or the demand or time / temperature when outdoor unit temperature is out of sensor defrost operation. (System will still control detects proper range. heat or cool.) sensor readings. • Sensor being detected open or shorted or temperature is out of sensor range. 417 Moderate The outdoor unit discharge line Replace faulty sensor Outdoor Unit • Outdoor unit control will not / Critical sensor is either open, and perform a system short-circuited or the perform demand or time / power reset. temperature is out of sensor temperature defrost operation. range. (System will still heat or cool.) • Outdoor unit control detects open or shorted sensor, or temperature that is out of sensor range. • Critical alert after 10 minutes. • Reset by replacing sensor. • This fault is detected by allowing the unit to run for 90 seconds before checking sensor resistance. • If the sensor resistance is not within range after 90 seconds, the board will count one fault. • After five faults, the outdoor control will lock out. • Check for proper sensor reading and attachment to line. • Replace outdoor control or sensor if out-of-specifications.

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code NOTE: Confirm there are no shorts or opens in the Comfort Sync® thermostat connections to any of the other components in the communication system. 418 Moderate There is a faulty W output circuit. Automatically clears Equipment • W terminal is energized while in interface module after fault signal is cooling mode. and outdoor unit removed. • Possible cause may be a stuck closed relay on the control, or something external to the control that is energizing W terminal when it should not be energized. • Disconnect any wiring from the W terminal. • If 24VAC is still on the terminal, then it is a stuck relay. • If 24VAC disappears, then there is a need to check any of the wires hooked up to the W terminal. 419 Critical The W output has reported more Automatically clears Equipment • The system will shut down the interface module than five errors. after power recycled. outdoor unit. and outdoor unit • The W output (code E418) on the outdoor unit has reported more than five strikes. • Disconnect thermostat lines from W and verify 24VAC on the W. • If 24VAC is present, replace the outdoor control. 420 Critical The heat pump defrost cycle has Automatically clears Air handler or • Defrost cycle lasts longer than 20 equipment taken more than 20 minutes to when W1 signal is minutes. interface module complete. removed.

31 Comfort Sync 7-Day Programmable Communicating Thermostat

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code • Check heat pump operation. • This is applicable only in communicating indoor unit with non-communicating heat pump. 421 Critical The W output terminal on the Equipment Voltage sensed on W output terminal Automatically clears outdoor unit is not wired interface module when Y1 out is deactivated. once voltage is not correctly. and outdoor unit sense on output for power cycled. 422 Moderate Outdoor unit Compressor top cap switch Automatically clears Check condenser fan motor, TXV exceeding thermal limit. • when error is corrected. and indoor unit blower motor. • Check for stuck reversing valve or clogged refrigerant filter. • XC/XP20 and XC/XP25: Check to ensure that one of the wires from the top cap switch has not been disconnected from one of the TP terminals on the outdoor control. Reconnect wire if disconnected.

423 Moderate / Outdoor unit The inverter has detected a • When this condition is detected the • A moderate alarm Critical circuit issue. outdoor control will stop outdoor will clear unit operations and start the automatically when anti-short cycle timer – moderate the inverter detects condition. the condition no longer exist and will Outdoor control will lockout unit • send a clear alarm after 10 strikes within an hour – message. critical condition. • To clear critical alarm disconnect power to outdoor unit and restart.

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code 424 Moderate Outdoor unit The liquid line temperature Automatically clears In normal operation after outdoor sensor has malfunctioned. • upon configuration, or control recognizes sensors, the sensing normal values. alert code will be sent if a valid temperature reading is lost. • Compare liquid line sensor resistance to temperature / resistance charts in unit installation instructions. • Replace sensor pack if necessary. • At the beginning of (any) configuration, furnace or air handler control will detect the presence of the sensor(s). • If detected (reading in range), appropriate feature will be set as 'installed' and shown in the Comfort Sync® Wi-Fi® thermostat 'About' screen. 425 Minor Outdoor unit Outdoor control has increased Automatically clears Outdoor ambient temperature is minimum compressor speed to • when outdoor ambient allow for proper oil return due to below system limit. temperature rises above low ambient temperature. • Control will attempt to run at lowest limit for more than five allowed compressor speed to allow minutes. for proper oil return. 426 Critical Outdoor unit Excessive inverter alarms. To clear disconnect After ten faults within one hour • power to outdoor control outdoor control will lockout. and restart • Inverter alarms 12 to 14 and 53 do not count towards this lockout condition. 427 Moderate / Outdoor unit The inverter has detected a DC To clear, disconnect • If condition (55A or higher) is and reconnect power to

33 Comfort Sync 7-Day Programmable Communicating Thermostat

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code Critical peak fault condition. detected, outdoor unit will stop outdoor control. (compressor and fan) – moderate condition. • Anti-short cycle is initiated. • If peak current (55A or higher) occurs 10 times within an hour, system will lockout – critical condition.

428 Moderate / Outdoor unit The inverter has detected a high To clear, disconnect • If condition is detected, outdoor unit Critical main input current condition. power to outdoor unit will stop (compressor and fan) – and restart. moderate condition. • Anti-short cycle is initiated. • If condition occurs 10 times within an hour, system will lockout – critical condition.

429 Moderate / Outdoor unit The inverter has detected a DC Automatically clears • On a call for compressor operation, Critical link low voltage condition. when the system if DC link power in inverter does detects that the issue no not rise above 180 VDC for 2- and 3 longer exists. -ton models, 250 VDC for 4- and 5-ton models within 30 seconds, the control will display a moderate code. • If condition is detected, outdoor unit will stop (compressor and fan) – moderate condition. • An anti-short cycle timer is initiated. If condition occurs 10 times within a 60 minute rolling time period, system will lock out and display alert code 429 – critical condition. • The outdoor control anti-short cycle 34

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code timer will time out and the unit will recycle the demand. • Replace outdoor inverter.

430 Moderate / Outdoor unit Compressor start-up failure To clear, disconnect If condition is detected, outdoor unit Critical • power to outdoor unit will stop (compressor and fan) – and restart. moderate condition. • Anti-short cycle is initiated. • If condition occurs 10 times within an hour, system will lockout – critical condition.

431 Moderate / Outdoor unit The inverter has detected a PFC To clear, disconnect • Error occurs when PFC detects an Critical circuit over-current condition. power to outdoor unit over current condition of 100A and restart. peak. • If condition is detected, outdoor unit will stop (compressor and fan) – moderate condition. • Anti-short cycle timer is initiated. • If condition occurs 10 times within an hour, system will lockout – critical condition.

432 Moderate / Outdoor unit The inverter has detected a DC To clear, disconnect Error occurs when the DC link Critical link high voltage condition. • power to outdoor unit capacitor voltage is greater than and restart. 480VDC. • If condition is detected, outdoor unit will stop (compressor and fan) – moderate condition. • Anti-short cycle timer is initiated. • If condition occurs 10 times within

35 Comfort Sync 7-Day Programmable Communicating Thermostat

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code an hour, system will lockout – critical condition.

433 Moderate / Outdoor unit Compressor phase current is too To clear alert code Error occurs when compressor Critical high. • disconnect power to peak phase current is greater than outdoor unit and restart. 28A. • Inverter will issue code 14 first and slow down to try to reduce the current. • If the current remains high, outdoor unit will stop (compressor and fan) – moderate condition. • Anti•short cycle timer is initiated. • If condition occurs five times within an hour, system will lockout – critical condition.

434 Moderate / Outdoor unit Outdoor control has lost Automatically clears Outdoor control has lost Critical communications with the inverter • when the system communications with the inverter for greater than three minutes. detects that the issue no for greater than three minutes. longer exists. • Outdoor control will stop all compressor demands – moderate condition. • Recycle power to the inverter by de-energizing the contactor for two minutes. • If this occurs three times in one thermostat call, the outdoor unit will locked out and display alert code 434 – critical condition. • Check for loose or disconnected electrical connections.

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code • Interruption of main power to inverter.

435 Moderate / Outdoor unit Inverter internal error. To clear alert code When this error occurs, the outdoor Critical • disconnect power to control will cycle power to the outdoor unit and restart. inverter by opening the contactor for two minutes – moderate condition. • Outdoor control will cycle power to the inverter three times and then outdoor unit is locked out – critical condition.

436 Moderate / Outdoor unit Inverter heat sink temperature • This occurs when the heat sink • Moderate condition Critical exceeded limit. temperature exceeds the inverter will automatically limit. Inverter will issue inverter alert clear when the code 13 first and slow down to try to inverter sends an cool the heat sink. alarm clear message. • If temperature remains high, outdoor unit will stop both • Critical condition is compressor and fan – moderate cleared by condition. disconnecting power to the outdoor unit Anti•short cycle is initiated. • and restart. • If condition occurs five times within an hour, system will lockout – critical condition. • Feedback from supplier tear down of inverter indicates that the screws that hold the inverter to the inverter board were loose causing poor contact between these two components. • Tighten screws that hold the heat

37 Comfort Sync 7-Day Programmable Communicating Thermostat

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code sink to the inverter control board. NOTE: Wait five minutes to all capacitor to discharge before checking screws. 437 Moderate / Outdoor unit Heat sink temperature sensor When the temperature sensor Moderate priority Critical fault has occurred (temperature • • less than 4 ºF or greater than detects a temperature less than condition will 0.4ºF or greater than 264ºF after 10 automatically clear 264ºF after 10 minutes of minutes of operation. when the inverter operation). sends an alarm clear Outdoor unit will stop both • message. compressor and fan – moderate condition. • Critical priority condition can be Anti•short cycle is initiated. • cleared by • If condition occurs five times within disconnecting and an hour, system will lockout – reconnecting power critical condition. to outdoor unit to restart. 438 Moderate / Outdoor unit The inverter has detected a PFC • The inverter has detected a power • Moderate priority Critical circuit over-current condition. factor correction (PFC) over current condition is condition. This may be caused by a automatically high load condition, high pressure, cleared when the or outdoor fan failure. inverter sends a clear message. • Outdoor control will display the code when the inverter has • Critical priority detected the error – moderate condition will condition. automatically clear when inverter is After three minutes, the inverter will • power cycled. reset and the compressor will resume operation. • If the error condition occurs 10 times within a 60 minute rolling time period, the outdoor unit control will

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code lock out operation of the outdoor unit – critical condition. • Possible issue is system running at high pressures. • Check for high pressure trips or other alert codes in room thermostat and outdoor control.

439 Moderate Outdoor unit Compressor slowdown due to Automatically clears • Input current is approaching a high high input current. when the condition no limit. longer exists. • Compressor speed will automatically slow down. The outdoor control will continue sending the inverter speed demanded by the thermostat. • The outdoor control will set indoor CFM and outdoor RPM to values according to demand percentage rather than the actual Hz. 440 Moderate Outdoor unit Compressor slowdown due to Automatically clears • Heat sink temperature is high heat sink temperature. when the condition no approaching limit. longer exists. • The compressor speed automatically slows to reduce heat sink temperature. • The control sets indoor CFM and outdoor RPM to values according to demand percentage rather than the actual Hz. • Feedback from supplier tear down of inverter indicates that the screws that hold the inverter to the inverter board were loose causing poor

39 Comfort Sync 7-Day Programmable Communicating Thermostat

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code contact between these two components. • Tighten screws that hold the heat sink to the inverter control board. • NOTE: Wait five minutes to all capacitor to discharge before checking screws.

441 Moderate Outdoor unit Compressor slowdown due to Automatically clears Compressor slowdown due to high high compressor current. • when the condition no compressor current. longer exists. • Compressor current is approaching limit. • The compressor speed automatically slows. • The control sets indoor CFM and outdoor RPM to values according to demand percentage rather than the actual Hz. • Possible issue is system running at high pressures. • Check for high pressure trips or other alert codes in room thermostat and outdoor control.

442 Critical Outdoor unit The top cap switch has opened To clear, disconnect This condition occurs when five times within one hour. As a • power to outdoor unit result, the outdoor unit is locked compressor thermal protection and restart. sensor opens five times within one out. hour. • Outdoor unit will stop.

443 Critical Outdoor unit Incorrect appliance unit size Automatically clears Check for proper configuring under code selected. • after the correct match unit size code used for outdoor unit 40

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code (see unit configuration guide or in is detected following a installation instructions). power reset. • If replacing inverter, verify inverter model matches unit size. • Remove the thermostat from the system while applying power and reprogramming.

530 Moderate / Damper control Low Damper 24VAC Voltage • Damper supply voltage is Automatically clears Critical module when the condition less than 18VAC. no longer exists. • Maintain non-zone mode for five minutes after alarm clears.

532 Moderate Damper control Zoning Pressure Switch Opened Automatically clears • Compressor pressure is above the module (high pressure) after compressor specified limit. pressure is within • Compressor is turned off. limits. • Zoning will be restored once the high pressure switch closes.

542 Moderate/ Damper control Zone 1 Temperature Sensor Automatically clears 30 • Zone temperature sensor reading Critical module Problem seconds after condition out of range. no longer exist. 543 Moderate/ Damper control Zone 2 Temperature Sensor • Open or short zone temperature Critical module Problem sensor detected for more than five 544 Moderate/ Damper control Zone 3 Temperature Sensor second. Critical module Problem • Damper control module will operate

41 Comfort Sync 7-Day Programmable Communicating Thermostat

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code 545 Moderate/ Damper control Zone 4 Temperature Sensor in non-zone mode (all dampers Critical module Problem open) – moderate condition. • If after 10 minutes the condition does not change, the priority code is change to critical. System will continue to operate in non-zone mode. 594 Moderate / Pre-coil discharge air Alarm clears five Equipment • Interlock relay energized, but input Critical interface module temperature sensor problem minutes after fault (DFM mode only). Advances not sensed after three seconds. clears. from moderate to critical after • No heating and cooling operations. ten (10) minutes. • De-energize interlock relay and re-energized five minutes later if demand is still present. 600 Critical Outdoor unit Compressor has been cycled Automatically clears Load shedding function provides a OFF on utility load shedding. • when L terminal is method for a local utility company to inactive. limit the maximum power level usage of the outdoor unit. • The feature is activated by applying 24VAC power to the L and C terminals on the outdoor control. 601 Critical Outdoor unit Outdoor unit has been cycled Automatically clears This is a low temperature protection OFF on low temperature • when priority condition feature. protection. no longer exists. • Outdoor unit will not operate when the outdoor temperature is at or below •4°F (•20°C). • If the unit is operating and the outdoor temperature drops below •4°F (•20°C), the unit will continue to operate until the room thermostat is satisfied or the outdoor temperature

Alert Priority System Actual Displayed Alert Text Component or System Operational How to Clear Alert Code Condition Component State and Troubleshooting Tips Code drops to •15°F (•26°C). • Outdoor unit ambient sensor provides temperature readings). 602 Minor Low ambient conditions prevent Automatically clears Outdoor Unit Outdoor unit will not operate due to the use of the outdoor unit. • when priority outdoor ambient conditions. condition no longer exists. 700 Moderate The temperature sensor in the Automatically clears Thermostat Recalibrate thermostat to clear. thermostat is not working • when the system properly. • Replace thermostat if needed. detects that the issue no longer exists. 701 Moderate The thermostat is reading indoor Automatically clears Thermostat Recalibrate thermostat to clear temperatures above the • when the system pre-programmed limit. • Cool thermostat detects that the issue no longer exists. 702 Moderate Thermostat The thermostat is reading indoor • Adjust set point. temperatures below the pre-programmed limit. • Replace thermostat, if needed. 703 Moderate Thermostat The humidity sensor in the Automatically clears thermostat is not working when the system properly. detects that the issue no longer exists. 704 Moderate The thermostat is reading indoor Automatically clears Thermostat • Recalibrate thermostat to clear. humidity levels above the when the system pre-programmed limit. • Replace thermostat, if needed. detects that the issue 705 Moderate Thermostat The thermostat is reading indoor no longer exists. humidity levels below the pre-programmed limit.

43 Comfort Sync 7-Day Programmable Communicating Thermostat