18
Symptom
Possible Cause
Corrective Action
Motor will not start, runs slowly or
repeatedly trips out overload
protection.
1.
Pressure switch not turned
on.
2.
Air receiver tank pressure
above cut-in pressure.
3.
No voltage at the pressure
switch.
4.
No voltage at the electric
motor, (faulty pressure
switch or DOL starter)
5.
No voltage on one or two
phases of 415v supply.
6.
Low supply voltage.
7.
Thermal overload relay in
DOL starter tripped.
8.
Faulty pressure switch
unloader valve, (nil or
restricted unloading air flow.
9.
Nil or restricted discharge air
flow through non-return
valve.
10.
Damaged motor cowl and/or
fan, other motor faults.
11.
V-belts too tight or
misaligned.
12.
Compressor pump partially
or totally seized.
1.
Turn on pressure switch.
2.
Nil (no fault). Unit will start
when pressure drops.
3.
Check electricity supply
including all fuses, circuit
breakers, switches and
wiring.
4.
Repair or replace pressure
switch or DOL starter.
5.
Check voltage on all three
phases of 415v supply.
6.
Check no load and full load
supply voltage. Upgrade
power supply circuit if
required. Disconnect any
other appliances on the
same supply circuit.
7.
Allow motor to cool down
and manually reset overload
relay (located inside the
DOL starter).
8.
Replace unloader valve or
complete pressure switch.
9.
Repair or replace non-return
valve.
10.
Replace cowl and/or fan,
replace motor.
11.
Adjusts belts to proper
tension and alignment.
12.
Repair or replace
compressor pump.
Compressor pump does not come
up to speed.
1.
Loose motor pulley, loose
compressor flywheel or
loose/worn V-belts.
2.
Low supply voltage.
3.
Damaged or worn.
4.
Compressor pump partially
seized.
1.
Tighten or replace pulleys as
required, check alignment
and adjust V-belt tension.
2.
Check no load and full load
supply voltage. Upgrade
power supply circuit if
required. Disconnect any
other appliances on the
same supply circuit.
3.
Replace compressor pump
valves and or blown head
gaskets.
4.
Repair or replace
compressor pump.
