26
Troubleshooting (continued)
Problem
Possible Cause
Solution
The motor hums and runs
slowly or not at all.
□
The voltage supplied to the air
compressor unit is low or not
present.
□
Check the incoming voltage with a voltmeter. Check the overload
relay in magnetic starter or the reset switch on the motor. If the
overload or the reset switch trips repeatedly, find and correct the
cause.
□
The motor winding is shorted or
open.
□
Replace the motor.
□
The check valve or the unloader valve
is malfunctioning.
□
Replace the check valve or the unloader valve.
□
The pressure switch is
malfunctioning and the contacts will
not close.
□
Repair or replace the pressure switch.
The oil in the oil reservoir
of the pump is milky.
□
Water is condensing in the
crankcase due to high humidity.
□
Pipe the air intake to a less humid air source. Then run the air
compressor unit (A) continuously under no load for one hour. Open
the drain valve to prevent the air compressor unit from building
pressure.
There is excessive oil
consumption or oil in the
air lines of the air
compressor unit (A).
□
The air intake is restricted.
□
Clean or replace the air filter.
□
The oil in the pump is the wrong type
or viscosity.
□
Drain the air compressor unit (A) of oil. Refill with new oil of the
proper viscosity.
□
The piston rings are worn.
□
Replace the piston rings.
□
Oil leaks out of the pump.
□
Tighten the bolts, replace the gaskets or replace the o-rings of the
pump.
□
The cylinde is scored or damaged.
□
Replace the cylinder of the pump.
The air compressor
unit (A) builds up pressure
quickly.
□
There is excessive water in the tank.
□
Drain the tank.
Interstage safety valve
pops off when the unit is
running.
□
Valve problem or worn gasket.
□
Check and replace valve or gaskets.
□
Low head bolt torque.
□
Check and retighten head bolts to specified torque.
□
Defective interstage safety valve.
□
Replace interstage safety valve. Under no circumstances plug the
safety valve port.
