Troubleshooting Chart
Symptom
Possible Cause(s)
Excessive noise in
1. Loose pulley, flywheel, belt, belt
operation
guard, etc
2. Lack of oil in crankcase
3. Compressor floor mounting loose 3. Shim to level and tighten or place on islolator pads
4. Malfunctioning check valve
5. Unit not on vibration pads
Milky oil in oil
Water condensing in crankcase due
reservoir
to high humidity
Excessive oil
1. Be sure there is a problem
consumption or oil
in air lines
2. Restricted air intake
3. Wrong oil viscosity
4. Worn piston rings
5. Oil leaks
6. Scored cylinder
Water in discharge
1. Excessive water in tank
air
2. Hot, humid weather
Air blowing out of
Broken first stage inlet valve (two-
inlet
stage unit)
Insufficient pressure 1. Air demand too high
2. Leaks or restrictions in hoses or
piping
3. Slipping belts
Tank does not hold
1. Worn check valve
pressure when
compressor is off
and shutoff valve is
2. Check all connections and fittings
closed
for tightness
3. Check tank for cracks or pin holes 3. Replace tank. Never repair a damaged tank
Excessive belt wear.
1. Pulley out of alignment
(Light dust from
2. Belts too tight or too loose
start is normal.
Worn belts separate
at layers)
Tank pressure builds
1. Dirty air filter
slowly
2. Blown cylinder head gasket
3. Worn/broken intake/discharge
valves
4. Air leaks
Tank pressure
Excessive water in tank
builds up quickly on
compressor
ASME safety valve
1. Pressure switch exceeding
pops open while
maximum pressure
compressor is
2. Malfunctioning ASME safety valve 2. Replace ASME safety valve
running
3. Pressure switch contacts welded
Pressure switch
Malfunctioning check valve
continuously blows
air out the unloader
valve
Pressure switch
Malfunctioning unloader valve on
unloader valve does
pressure switch
not release air when
the unit shuts off
Interstage safety
1. Head gasket or the gasket in the
valve pops off while
valve plate assembly blown
the unit is running
2. Valve not seating properly
3. Malfunctioning safety valve
Interstage safety
Malfunctioning tank check valve
valve pops off after
the unit shuts off
(Continued)
Corrective Action
1. Tighten
2. Check for damage to bearings, replenish oil
4. Replace check valve
5. Install vibration pads under compressor feet
Pipe air intake to less humid air source. Run pump
continuously for one hour
1. Diagnose oil contamination problems by testing the discharge air or
measuring oil consumption from the crankcase
2. Clean or replace air filter
3. Drain oil. Refill with oil of proper viscosity
4. Replace rings
5. Tighten bolts, replace gaskets or o-rings
6. Replace cylinder
1. Drain tank
2. Purchase dryer
Replace valve assembly
1. Limit air usage
2. Check for leaks or restriction in hose or piping
3. Tighten belts
1. Replace check valve
2. Tighten
1. Realign motor pulley
2. Adjust tension
1. Clean or replace filter element
2. Install new gasket
3. Install new valve plate assembly
4. Tighten joints
Drain tank, check speed. See Performance table
1. Replace pressure switch
3. Replace pressure switch
Replace the check valve if the unloader valve bleeds off constantly
Replace the pressure switch if the unit does not hiss for a short period
of time when the unit shuts off
1. Replace valve plate and gaskets
2. Replace valve plate and gaskets
3. Replace safety valve
Replace the check valve
7
Do not disassemble check valve with air
in tank
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HS5180