Air Compressor Piston Trouble Shooting Guide www.IndustrialAirCompressor.biz

TROUBLE PROBABLE CAUSE CORRECTIVE ACTION Motor Will Not Run. ƒ Power not on Turn power on

(Failure to start) ƒ Blown main fuses (size 175% of motor nameplate) Replace fuses

ƒ Blown control fuses (size per nec article 450-3) Replace fuses 1 ƒ Breaker tripped Reset or replace breaker

ƒ Safety device tripped Reset safety devices

ƒ Motor starter overloads tripped Reset or replace overloads

ƒ Faulty motor starter coil Replace starter coil

ƒ Pressure switch incorrectly set Adjust pressure switch

ƒ Pressure switch defective Replace pressure switch

ƒ Start switch contacts defective Replace start switch

ƒ Auxiliary contacts defective Replace Auxiliary

ƒ Loose electrical wire Tighten electrical wires

ƒ Wire broken or off terminal Replace wire or reconnect

ƒ Thermal overload inside motor tripped Reset or replace motor

ƒ Low voltage Must be 10 % of nameplate

ƒ Motor defective Replace motor

ƒ Wiring incorrect Correct wiring

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TROUBLE PROBABLE CAUSE CORRECTIVE ACTION Starter Trips Repeatedly ƒ Low voltage (must be within 10% of nameplate Check voltage @ disconnect

Excessive current ƒ Wrong heater size (check heater amps) Replace heaters elements draw (To determine ƒ Wrong overload setting (check motor amps) Adjust overload setting maximum amperage allowed, multiply the ƒ Loose electrical connection Tighten all wire connections FLA on the motor nameplate by the ƒ Wire size too small Install correct size wire service factor.) ƒ Motor defective Replace motor 2 ƒ Motor sized incorrectly Resize & replace motor

ƒ Pressure switch unloader defective Replace pressure switch

ƒ Centrifugal Unloader valve defective Replace valve

ƒ Electric solenoid unloader valve defective Replace valve

ƒ Hydraulic unloader valve defective Replace valve

ƒ In-tank check valve defective Replace valve

ƒ Unloaders not unloading suction valves Check for pressure / rebuilt

ƒ Defective compressor valves Replace compressor valves

ƒ Unloader control line plugged Replace control line

ƒ Discharge pressure too high Adjust switch or replace

ƒ Drive belts too tight Adjust to correct tension

ƒ Head gasket blown between the cylinders Replace head gasket

ƒ No crankshaft endplay (.001 per inch of bearing od) Adjust bearings tolerance

ƒ Rod bearing tight or seizing (.001 per inch diameter) Replace bearings or rods

ƒ Pistons seizing to cylinders Replace pistons / rebuilt

ƒ Incorrect oil Change to correct weight

ƒ Intercooler plugging (30-50) psig normal Remove clean or replace

ƒ Compressor unit seized (locked up) Remove & disassemble unit

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TROUBLE PROBABLE CAUSE CORRECTIVE ACTION Pressure Switch ƒ Moisture build up on the switch diaphragm Replace pressure switch Defective ƒ Ruptured diaphragm (air leak) Replace pressure switch 3 ƒ Burned contact points Replace pressure switch

ƒ Unloader valve leaking (when running) Replace pressure switch

ƒ Pressure setting changes Replace pressure switch

ƒ Plugged air passage in unloader valve Replace pressure switch

Pilot Valve Unloader Pilot valve unloader unloads at to low or high pressure Adjust pilot unloader valve Defective 4 Pilot valve unloader loads/unloads excessively Adjust pilot unloader valve

Pilot valve unloader leaking when running Replace pilot unloader valve

Pilot valve unloader leaking when stopped Replace pilot unloader valve

ELECTRIC Solenoid leaking @ exhaust port when stopped Replace electric solenoid valve SOLENOID UNLOADER Solenoid leaking @ cylinder port when running Replace electric solenoid valve VALVE 5 Solenoid does not click when electricity is applied Replace electric solenoid valve

Centrifugal Unloader ƒ Centrifugal Unloader valve leaking when running Adjust or replace unloader Leaking 6 ƒ Centrifugal Unloader valve leaking when stopped Replace in-tank check valve

Hydraulic ƒ Hydraulic unloader valve passes air to suction Adjust oil pressure to 25 psig Unloader unloader when running oil pressure less than 15 psig Faulty 7 ƒ Hydraulic unloader valve passes air to suction Replace hydraulic unloader unloader when running with 25 psig oil pressure

ƒ Hydraulic unloader passes no air to suction unloader Replace hydraulic unloader when not running

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TROUBLE PROBABLE CAUSE CORRECTIVE ACTION Intercooler relief ƒ Safety Relief valve defective (set 45-100 psig ) Replace Safety relief valve valve pops off (the two stage ƒ Relief Valve pops off when running & pumping Replace unloaders or valves models) 8 ƒ Valve pops off when running & not pumping Replace unloaders or valves

ƒ Valve pops off when not running Replace unloaders or valves

ƒ Intercooler restricted or plugged Clean or replace intercooler

Intercooler pressure ƒ Defective pressure gauge Replace air pressure gauge abnormally low (Two stage models ƒ Leaking intercooler connections Tighten connection only) ƒ Leaking intercooler Replace intercooler 9 ƒ Compressor valves in L.P. defective Replace valves

ƒ Suction Unloaders in L.P. defective Rebuild or replace

ƒ Restricted air inlet filter Replace inlet filter

ƒ Compressor valve defective Replace compressor valves

ƒ Pilot valve defective Replace pilot valve

ƒ Hydraulic valve not functioning properly Replace hydraulic unloader

ƒ Electric solenoid valve not functioning properly Replace solenoid valve

ƒ Worn piston rings Replace piston rings

Discharge Safety ƒ Relief valve defective (set 150% of tank psig) Replace relief valve Valve Pops Off ƒ Restricted in-tank check valve Replace check valve 10 ƒ Restricted discharge pipe Clean or replace pipe

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TROUBLE PROBABLE CAUSE CORRECTIVE ACTION Excessive air ƒ Air pressure gauge inaccurate Replace air pressure gauge pressure in air receiver ƒ Leaks in unloader piping system Repair leaks in control piping

11 ƒ Defective compressor suction unloaders Repair or replace unloader

ƒ Pilot valve set incorrectly or defective Adjust or replace valve

ƒ Pressure switch set incorrectly or defective Adjust or replace switch

ƒ Pressure switch wired incorrectly Correct wiring

ƒ Hydraulic valve not functioning properly Replace hydraulic valve

ƒ Electric solenoid valve not functioning properly Replace solenoid valve

ƒ Tube to compressor unloader valve plugged Replace control air line

Tank Pressure Builds ƒ Air pressure gauge inaccurate Replace air pressure gauge Too Fast 12 ƒ Tank full of water Drain water from tank

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TROUBLE PROBABLE CAUSE CORRECTIVE ACTION Tank Pressure Raises ƒ Defective pressure gauge Replace pressure gauge Slowly 13 ƒ Restricted air inlet filter Replace inlet filter

ƒ Pressure switch defective Replace pressure switch

ƒ Pressure switch set wrong Adjust pressure switch

ƒ Unloader pilot defective Replace pilot valve

ƒ Unloader pilot set wrong Adjust pilot valve

ƒ Faulty hydraulic unloader Replace hydraulic unloader

ƒ Electric solenoid valve not functioning properly Replace solenoid valve

ƒ Centrifugal Unloader valve leaking when running Replace centrifugal valve

ƒ Defective compressor valves Replace compressor valves

ƒ Leaking head gasket Replace head gasket

ƒ Loose compressor valves leaking at valve gaskets Replace valve gasket

ƒ Low oil pressure Adjust oil pressure

ƒ Drive belt slipping Adjust belt tension

ƒ Incorrect speed Change motor pulley

ƒ Clogged intercooler (internal) Clean or replace

ƒ Excessive running clearances Rebuilt compressor pump

ƒ Worn piston rings or loose piston Rebuilt compressor pump

ƒ Leaks in the compressed air distribution system Find & Repair air leaks

ƒ Drain valve open Close drain valve

ƒ Pressure relief valve leaking Replace relief valve

ƒ Compressor incorrectly sized for the altitude Install larger compressor

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TROUBLE PROBABLE CAUSE CORRECTIVE ACTION Compressor loads ƒ Pressure switch defective Replace pressure switch and unloads excessively ƒ Pilot valve set incorrectly or defective Replace pilot valve 14 ƒ Electric solenoid valve not functioning properly Replace solenoid valve

ƒ Compressor valves defective Replace compressor valves

ƒ Suction unloaders leaking Repair leaking unloader

ƒ Compressor operating at incorrect speed Install correct pulley

ƒ Excessive system leakage Repair air leaks

ƒ Air receiver tank too small Install larger receiver tank

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Low Oil Pressure ƒ Defective pressure gauge Replace oil gauge

15 ƒ Low oil level Add oil to full mark

ƒ Oil pump direction reversed Change rotation

ƒ Oil sump strainer plugged Clean or replace strainer

ƒ Plugged oil filter Replace oil filter

ƒ Leakage at mains & rod bearings Rebuilt compressor pump

ƒ Oil pressure adjusting screw not set properly Adjust oil pressure to spec

TROUBLE PROBABLE CAUSE CORRECTIVE ACTION

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Excessive Oil ƒ Compressor runs unloaded too long Run in start/stop position consumption ƒ Worn piston rings Replace ring 16 ƒ Restricted intake system Replace inlet filter

ƒ Compressor running too hot See high discharge temp

ƒ Breather valve not functioning properly Replace breather valve

ƒ Oil level in crankcase too high Drain to proper oil level

ƒ Oil viscosity wrong for the application Change to correct viscosity

ƒ Connecting rod out of alignment, bent or twisted Replace connecting rods

ƒ Leaking oil seal Replace shaft oil seal

ƒ Piston rings not seated (300 hours for seating) Change to non detergent oil

ƒ Wrong oil ( detergent oil has a tendency to foam) Use air compressor oil

High Discharge ƒ Defective temperature gauge or switch Replace temp gauge or switch Temperature ƒ Compressor valve assemblies defective Replace compressor valves 17 ƒ Pulley/sheave rotation wrong Change rotation

ƒ Discharge pressure too high Adjust pressure lower

ƒ Ambient temperature too high Lower ambient temperature

ƒ Inadequate ventilation or hot air recirculating Vent hot air out of room

ƒ Cooling surfaces of compressor excessively dirty Clean cooling fins

ƒ Intercooler excessively dirty internal or external Clean internal & external

ƒ Defective water temperature regulating valve Replace water regulating val

ƒ Clogged water passages in head &/or cylinders Clean water passages

ƒ Inadequate cooling water flow Increase water flow

ƒ Cooling water temperature too hot Lower temperature of water

ƒ Lubrication inadequate Use air compressor oil

ƒ Running clearances insufficient Change clearances

High Discharge ƒ Scored or excessively worn cylinder walls Replace cylinder Temperature

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(continued) ƒ Incorrect speed Change motor pulley

ƒ Compressor incorrectly size Install larger compressor

TROUBLE PROBABLE CAUSE CORRECTIVE ACTION Compressor knocks ƒ Loose belts Adjust belts ƒ 18 Head clearance insufficient Check piston to head clearance

ƒ Piston loose in cylinder bore worn piston rings Rebuilt compressor pump

ƒ Worn rods or main bearing Rebuilt compressor pump

ƒ Pressure setting excessive high Adjust to lower pressure

ƒ Crankcase lubrication inadequate Correct lubrication problem

ƒ Loose pulley/sheave Tighten pulley & sheave

Compressor valve assemblies loose Tighten compressor valves

Loose compressor or motor mounting bolts Tighten mounting bolts

In-tank check defective Replace check valve

Excessive drive belt ƒ Pulley/sheave out of alignment Realign pulley & sheave wear 19 ƒ Belt too loose or too tight Adjust to correct tension

ƒ Belt slipping Replace belts

ƒ Pulley/sheave wobbling Tighten to shafts

ƒ Pulley/sheave groove damaged or worn Replace pulley & sheave

ƒ Incorrect belts Replace with correct belts

Excessive vibration ƒ Compressor feet not level Shim compressor feet

20 ƒ Compressor tightened into a bind Retighten & shim

ƒ Motor or engine not secured tightly Tighten motor secure

ƒ Foundation or frame inadequate Install correct foundation

ƒ Piping inadequately supported Install additional support

ƒ Piping tightened into a bind Install flexiblemetal hose

ƒ Excessive discharge pressure Lower pressure setting

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ƒ Loose pulley/sheave Tighten pulley & sheave

ƒ Incorrect speed Change to correct rpms

Excessive vibration ƒ Compressor valves not functioning properly Replace compressor valves (continued) 20 Motor or engine out of balance Balance motor or engine

TROUBLE PROBABLE CAUSE CORRECTIVE ACTION Rusty valves and/or ƒ Compressor operated too infrequently Run compressor more cylinders ƒ Compressor does not run long enough to get hot Install smaller compressor 21 ƒ Leaking water jacket or cylinder head Repair water leak

ƒ Cooling water circulating in compressor too cold Replace water regulator valve

ƒ System pressure leaking back through compressor Re-pipe & add a check valve

Water in the ƒ Compressor does not run long enough to get hot Install smaller compressor crankcase (lubricant appears ƒ System pressure leaking back through compressor Re-pipe & add a check valve milky) 22 ƒ Leaking water jacket or cylinder head Repair water leak

ƒ Cooling water circulating in compressor too cold Replace water regulator valve

ƒ Incorrect or inferior grade of lubricant Use air compressor oil

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