Piper ARROW III Service Manual page 418

TABLE X-I. TROUBLESHOOTING CHART (VACUUM SYSTEM) (cont)
Trouble
Vacuum correct but pilot
reports erratic indication
of complete loss in flight.
Vacuum can only be
maintained at full
throttle on ground.
AUX ON selected on
ground check and
auxiliary vacuum pump
will not run.
AUX ON selected on
ground check and little
or no vacuum is indicated.
AUX ON annunciator will
not illuminate.
VAC OFF AUX ON
annunciator switch will
not engage auxiliary
vacuum pump system.
Auxiliary vacuum pump
maintains correct pressure
on the ground but not at
altitude.
Revised: 2/13/89
CHEROKEE ARROW III SERVICE MANUAL
Regulator sticky.
Oil in pump due to leaky
engine flange seal or
cleaning fluid blown into
pump while cleaning engine.
Leak in system.
Worn pump.
Stuck regulator.
Circuit breaker open.
Faulty electric motor.
Faulty contactor.
Loose or broken wire
connections.
Leak in vacuum system.
Restriction in hose lines.
Dirty filter.
Faulty bulb.
Regulator not adjusted
properly.
Open circuit breaker.
Faulty switch.
Auxiliary vacuum pump
is worn out.
Regulator is sticky.
Cause
2F20
Remedy
Clean regulator.
Replace pump.
Repair or replace lines.
Replace pump.
Clean or replace regulator.
Reset circuit breaker(s).
Isolate and check operation.
Replace pump motor
assembly if required.
Tighten all wire connections
and terminals.
Check all wire for open
breaks; repair as needed.
Tighten clamps and check
hoses. Replace if necessary.
Inspect and repair hole lines.
Replace if necessary.
Replace filter.
Replace bulb.
Adjust properly.
Push circuit breaker(s) in.
Test switch for operation.
Replace if necessary.
Replace auxiliary vacuum
pump assembly.
Clean or replace regulator.
INSTRUMENTS