CAUTION: ALWAYS DISCONNECT ELECTRICAL POWER AND REMOVE AIR PRESSURE FROM SYSTEM BEFORE PERFORMING SERVICE ON ANY AIR COMPRESSOR.

 

Low Capacity
 
Low or No Oil Pressure Erratic Oil Pressure Piston Rod Packing Failure
       
Motor Overheats Crosshead Pin Bushing Failure Compressor Knocks Low First Stage Discharge Pressure
       
Low Second Stage Discharge Pressure Low Third Stage Discharge Pressure High First Stage Discharge Pressure High Second Stage Discharge Pressure
       
High Third Stage Discharge Pressure High First Stage Discharge Air Temperature High Second Stage Discharge Air Temperature High Final Discharge Air Temperature
       
Low or No Condensate from Drain Traps Too Much Condensate from Drain Traps First Stage Relief Valve Lifting Second Stage Relief Valve Lifting
       
Third Stage Relief Valve Lifting      

Low Capacity
  1. Restricted air suction line or filter.
  2. Loose valve assembly.
  3. Leaking valve assembly.
  4. Defective inlet valve unloaders.
  5. Defective or improperly set load controller.
  6. Worn Piston rings.
  7. Excessive leakage at piston rod packing.
  8. V-belts slipping (where applicable).

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Low or No Oil Pressure
  1. Defective pressure gauge or sensor.
  2. Crankcase oil level too low.
  3. Oil viscosity too light.
  4. Plugged oil filter.
  5. Leak in oil pump suction line.
  6. Incorrect oil pump relief valve setting.
  7. Oil pressure relief valve not seating.
  8. Broken relief valve spring.
  9. Defective oil pump.
  10. Oil pump drive coupling broken.
  11. Incorrect rotation (certain models).
  12. Worn main, crankpin or wrist pin bearings.

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Erratic Oil Pressure
  1. Defective gauge or sensor.
  2. Worn main, crankpin or wrist pin bearings.

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Piston Rod Packing Failure
  1. Scored or worn piston rod.
  2. Normal packing wear.
  3. Incorrect packing ring side clearance.
  4. Excessive piston rod runout.
  5. Restricted water flow thru case (water cooled only).

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Motor Overheats
  1. Discharge pressure too high.
  2. Worn or broken valves.
  3. Abnormal interstage pressures.
  4. Inadequate crankcase lubrication.
  5. Voltage incorrect.
  6. Excessive belt tension.
  7. Ambient air temperature over 104oF.
  8. Motor single phased or shorted.
  9. Motor cooling air intake screen dirty.

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Crosshead Pin Bushing Failure (Repeated)
  1. Excessive operation at 50% load.
  2. Bent connecting rod.

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Compressor Knocks
  1. Inadequate running clearances.
  2. Insufficient head clearance.
  3. Excessive crosshead clearance.
  4. Loose piston rod nut.
  5. Loose compressor pulley.
  6. Excessive bearing clearance.
  7. Discharge pressure too high.
  8. Loose valve.
  9. Excessive piston to cylinder clearance.
  10. Valve debris lodged in piston face.
  11. Bent connecting rod.
  12. Worn or broken piston rings.

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Low First Stage Discharge Pressure
  1. Defective pressure gauge or sensor.
  2. Dirty or restricted air filter.
  3. Loose or leaking first stage suction valves.
  4. Defective or sticking first stage discharge valves.
  5. Loose or leaking first stage discharge valves.
  6. Worn first stage piston rings.
  7. First stage intercooler drain valve stuck open.

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Low Second Stage Discharge Pressure
  1. Defective pressure gauge or sensor.
  2. Loose or leaking second stage suction valves.
  3. Defective or sticking second stage suction valve unloaders.
  4. Loose or sticking second stage discharge valves.
  5. Worn second stage piston rings.
  6. Second stage intercooler drain valve stuck open.

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Low Third Stage Discharge Pressure
  1. Defective pressure gauge or sensor.
  2. Loose or leaking third stage suction valves.
  3. Defective or sticking third stage suction valve unloaders.
  4. Loose or leaking third stage discharge valves.
  5. Worn third stage piston rings.
  6. Aftercooler drain valve stuck open.
  7. Plant demand greater than compressor capacity.
  8. Load controller set too low or defective.

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High First Stage Discharge Pressure
  1. Defective pressure gauge or sensor.
  2. Loose or leaking second stage suction valves.
  3. Defective or sticking second stage suction valve unloader.
  4. Worn second or third stage piston rings.
  5. Final discharge pressure too high.

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High Second Stage Discharge Pressure
  1. Defective pressure gauge or sensor.
  2. Loose or leaking third stage suction valves.
  3. Defective or sticking third stage suction valve unloader.
  4. Worn third stage piston rings.
  5. Final discharge pressure too high.

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High Third Stage Discharge Pressure
  1. Defective pressure gauge or sensor.
  2. Restriction in discharge air line.
  3. Incorrect setting or defective load controller.
  4. Control air not getting to suction valve unloaders.

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High First Stage Discharge Air Temperature
  1. Defective temperature gauge or sensor.
  2. Loose or leaking first stage valves.
  3. Defective or sticking first stage suction valve unloader.
  4. Insufficient cooling water.
  5. Cooling water temperature too high.
  6. Cylinder water jackets plugged.
  7. Worn first stage piston rings.
  8. Fouled first stage intercooler.
  9. High inlet air temperature.

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High Second Stage Discharge Air Temperature
  1. Defective temperature gauge or sensor.
  2. Loose or leaking second stage valves.
  3. Defective or sticking second stage suction valve unloader.
  4. Insufficient cooling water.
  5. Cooling water temperature too high.
  6. Cylinder water jackets plugged.
  7. Worn second stage piston rings.
  8. Fouled second stage intercooler.
  9. High second stage suction temperature.

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High Final Discharge Air Temperature
  1. Defective temperature gauge or sensor.
  2. Loose or leaking third stage valves.
  3. Defective or sticking third stage suction valve unloader.
  4. Insufficient cooling water.
  5. Cooling water temperature too high.
  6. Cylinder water jackets plugged.
  7. Worn third stage piston rings.
  8. Fouled aftercooler.
  9. High third stage suction temperature.

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Low or No Condensate from Drain Traps
  1. Defective trap.
  2. Drain pipe to and from trap plugged.
  3. Compressor running unloaded.
  4. Intercooler or aftercooler not properly cooling.

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Too Much Condensate from Drain Traps
  1. Cooling water leak in first, second or third stage cylinder.
  2. Cooling water leak in first or second stage intercooler.
  3. Cooling water leak in aftercooler.

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First Stage Relief Valve Lifting
  1. Defective relief valve.
  2. First stage intercooler plugged.
  3. Loose or leaking valves in second stage.
  4. Defective or sticking second stage suction valve unloaders.

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Second Stage Relief Valve Lifting
  1. Defective relief valve.
  2. Second stage intercooler plugged.
  3. Loose or leaking valves in third stage.
  4. Defective or sticking third stage suction valve unloaders.

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Third Stage Relief Valve Lifting
  1. Defective relief valve.
  2. Aftercooler plugged.
  3. Final discharge pressure too high.

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