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
reservoir
Water condensing in crankcase due
to high humidity
Pipe air intake to less humid air source. Run pump
continuously for one hour
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
Excessive belt wear.
(Light dust from
start is normal.
Worn belts separate
at layers)
1. Pulley out of alignment
1. Realign motor pulley
2. Belts too tight or too loose
2. Adjust tension
Tank pressure builds
slowly
1. Dirty air filter
1. Clean or replace filter element
2. Blown cylinder head gasket
2. Install new gasket
3. Worn/broken intake/discharge
valves
3. Install new valve plate assembly
4. Air leaks
4. Tighten joints
Tank pressure
builds up quickly on
compressor
Excessive water in tank
Drain tank, check speed. See Performance table
ASME safety valve
pops open while
compressor is
running
1. Wrong pressure switch setting
1. Adjust to lower pressure (175 psi maximum for two-stage unit or
135 psi for single stage unit) (See Operation)
2. Malfunctioning ASME safety valve 2. Replace ASME safety valve
3. Pressure switch contacts welded
3. Replace pressure switch
Pressure switch
continuously blows
air out the unloader
valve
Malfunctioning check valve
Replace the check valve if the unloader valve bleeds off constantly
Pressure switch
unloader valve does
not release air when
the unit shuts off
Malfunctioning unloader valve on
pressure switch
Replace the pressure switch if the unit does not hiss for a short period
of time when the unit shuts off
Interstage safety
valve pops off while
the unit is running
1. Head gasket or the gasket in the
valve plate assembly blown
1. Replace valve plate and gaskets
2. Valve not seating properly
2. Replace valve plate and gaskets
3. Malfunctioning safety valve
3. Replace safety valve
Interstage safety
valve pops off after
the unit shuts off
Malfunctioning tank check valve
Replace the check valve
Operating Instructions
8
Troubleshooting Chart
(Continued)
Symptom
Possible Cause(s)
Corrective Action
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