Symptom
Possible Cause(s)
Excessive belt wear.
1. Pulley out of alignment
(Light dust from start
2. Belts too tight or too loose
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 3. Install new valve plate assembly
4. Air leaks
Tank pressure
Excessive water in tank
builds up quickly on
compressor
ASME safety valve
1. Pressure switch setting to high
pops open while
2. Malfunctioning ASME safety valve
compressor is 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 valve
1. Head gasket or the gasket in the
pops off while the unit
valve plate assembly blown
is running
2. Valve not seating properly
3. Malfunctioning safety valve
Interstage safety valve
Malfunctioning tank check valve
pops off after the unit
shuts off
Corrective Action
1. Realign motor pulley
2. Adjust tension
1. Clean or replace filter element
2. Install new gasket
4. Tighten joints
Drain tank, check speed. See Performance table
1. Replace pressure switch
2. Replace ASME safety valve
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
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