12
TROUBLESHOOTING CHART
Symptom
Possible Cause(s)
Corrective Action
Motor hums and runs
slowly or not at all
1. Low voltage or no voltage
1. Check with voltmeter, check overload relay in magnetic starter or reset
switch on motor. If overload or reset switch trips repeatedly, find and
correct the cause. See next item
2. Shorted or open motor winding
2. Replace motor
3. Malfunctioning check valve or
unloader valve
3. Replace check valve or unloader valve
4. Malfunctioning pressure switch -
contacts will not close
4. Repair or replace pressure switch
Reset mechanism
cuts out repeatedly or
fuses blow repeatedly
1. Pressure switch set too high
1. Replace pressure switch
2. Malfunctioning check valve
2. Clean or replace faulty valve
3. Incorrect fuse size or magnetic starter
heaters
3. Be sure that fuses and heaters are rated properly
4. Malfunctioning motor
4. Replace motor
5. Loose Wiring
5. Check all electrical connections
Excessive noise in
operation
1. Loose pulley, flywheel, belt, belt
guard, etc
1. Tighten
2. Lack of oil in crankcase
2. Check for damage to bearings, replenish oil
3. Compressor floor mounting loose
3. Shim to level and tighten or place on islolator pads
4. Malfunctioning check valve
4. Replace check valve
5. Unit not on vibration pads
5. Install vibration pads under compressor feet
Milky oil in oil
crankcase
1. Low usage of compressor - water is
condensing in the crankcase
1. Run the compressor continuously for 1 hour. The heat generated during
this running period will evaporate the moisture out of the oil
2. Wrong type of oil
2. Do not use SAE-30 automotive type oil. Using the wrong oil can cause
various problems with the pump and will void the warranty. Only use the
oils that the operating manual recommends
3. Improper environment
3. Unit should not be installed in a poorly vented area or exposed to
extreme cold or hot conditions. Normal operating range should be
between 32°F and 100°F
4. Rotation incorrect
4. Check to make sure the compressor is running the direction of the
flywheel arrow. Air flow should be so that the flywheel directs air across
the head of the pump. Standing in front of the compressor (non-belt
guard side) air should flow back to front
5. Slight leakage of tank check valve
5. Air cools and condensates, then leaks back into the pump. Draining tank
of air after use will normally take care of this situation
Excessive oil
consumption or oil in
air lines
1. Be sure there is a problem
1. Diagnose oil contamination problems by testing the discharge air or
measuring oil consumption from the crankcase
2. Restricted air intake
2. Clean or replace air filter
3. Wrong oil viscosity
3. Drain oil. Refill with oil of proper viscosity
4. Worn piston rings
4. Replace rings
5. Oil leaks
5. Tighten bolts, replace gaskets or o-rings
6. Scored cylinder
6. Replace cylinder
Water in discharge air 1. Excessive water in tank
1. Drain tank
2. Hot, humid weather
2. Purchase dryer
Air blowing out of inlet 1. Broken first stage inlet valve (two-
stage unit)
1. Replace valve assembly
2. Broken inlet valve (single stage unit)
2. Replace valve assembly
Insufficient pressure
1. Air demand too high
1. Limit air usage
2. Leaks or restrictions in hoses or
piping
2. Check for leaks or restriction in hose or piping
3. Slipping belts
3. Tighten belts
Tank does not hold
pressure when
compressor is off and
shutoff valve is closed
1. Worn check valve
1. Replace check valve
Do not disassemble check valve with air
in tank
2. Check all connections and fittings for
tightness
2. Tighten
3. Check tank for cracks or pin holes
3. Replace tank. Never repair a damaged tank
MAINTENANCE /
REP
AIR
TROUBLESHOOTING
OPERA
TION
ASSEMBL
Y
/
INST
ALLA
TION
SAFETY
/
SPECIFICA
TIONS
GETTING
ST
ARTED
