TROUBLESHOOTING GUIDE
Symptom
Compressor will not run
Motor hums but cannot run or
runs slowly
Fuses blow/circuit breaker trips
repeatedly
Thermal overload protector cuts
out repeatedly
Knocks, rattles, excessive
vibration
Tank pressure drops when
compressor shuts off
Air output lower than normal/low
discharge pressure
Excessive moisture in discharge
air
Compressor runs continuously
Excessive starting and stopping
(auto start)
Air leaking from unloader on
pressure switch
*
Do not disassemble check valve with air in tank; bleed the tank.
8
Possible Cause(s)
1. No electrical power
2. Blown fuse
3. Breaker open
4. Thermal overload tripped
5. Pressure switch bad
6. Check valve defective
1. Poor contacts, line voltage
incorrect
2. Shorted or open motor winding
3. Defective check valve or unloader 3. Replace or repair *
1. Incorrect size fuse, circuit
overloaded
2. Defective check valve or unloader 2. Replace or repair *
1. Low voltage
2. Clogged air filter
3. Lack of proper ventilation/room
temperature too high
4. Check valve malfunction
1. Leaking, broken, or loose valves
or restricted air passage
2. Defective pressure switch
unloader
3. Defective bearing on eccentric or
motor shaft
4. Cylinder or piston ring is worn or
scored
5. Loose bolts, tank not level
1. Loose connections (fittings,
tubing, etc.)
2. Loose drain valve
3. Check valve leaking
1. Clogged intake port
2. Air leaks in piping (on machine or
in outside system)
3. Broken inlet valves
4. Piston ring broken
5. Cylinder or piston ring is worn or
scored
1. Excessive water in tank
2. High humidity
1. Defective pressure switch
2. Excessive air usage
3. Worn piston ring
1. Excessive condensation in tank
2. Air leaks in piping (on machine or
in outside system)
3. Tank check valve leaking
Check valve stuck in an open
position
Corrective Action
1. Plugged in? Check fuse/breaker or motor overload
2. Replace blown fuse
3. Reset, determine cause of problem
4. Reset Thermal overload
5. Replace
6. Remove and replace check valve *
1. Check connections, check with voltmeter
2. Replace motor
1. Check for proper fuse, use time-delay fuse. Disconnect other
electrical appliances from circuit or operate compressor on its
own branch circuit
1. Check with voltmeter
2. Clean filter (See Maintenance section)
3. Move compressor to well ventilated area
4. Replace *
1. Replace
2. Replace or repair as necessary
3. Replace
4. Replace or repair as necessary
5. Tighten bolts, shim tank to level position
1. Check all connections with soap and water solution and tighten
2. Tighten
3. Disassemble check valve assembly, clean or replace *
1. Clean or replace
2. Replace leaking components or tighten as necessary
3. Have authorized service representative repair unit
4. Replace
5. Replace
1. Drain tank
2. Move to area of less humidity; use air line filter
1. Replace switch
2. Decrease air usage; compressor not large enough for air
requirement
3. Replace
1. Drain more often
2. Replace leaking components or tighten as necessary
3. Replace or repair as necessary *
Remove and replace check valve *