Thermo King 914970, Manual

Page: 153 / 186

153
Electric Standby (Optional) Diagnosis
Condition Possible Cause Remedy
Unit switch On—indicator lights
do not come On Battery discharged Charge or replace battery
Remote switch off Turn On switch (optional)
Circuit breaker or safety switch
open Push in button. Replace switch if
defective
Electric motor reset switch tripping Check for short circuit in unit wiring
(high voltage)
Fuse link blown Replace fuse link
Dirty battery terminals Clean and retighten terminals
Unit switch On—indicator lights
come On but electric motor does
not run Diesel/Electric switch on Diesel Move switch to Electric position
No standby power Provide power to unit; check power
at:
1. Power source
2. Power plug
3. Motor contactor hot side
4. Motor contactor load side
(contactor closed)
5. Overload relay
6. Motor terminals
Defective motor contactor Repair or replace motor contactor
Defective low oil pressure switch Replace low oil pressure switch
Overload relay tripping Check for shorted motor windings or
wires
Defective motor Replace motor
Batteries discharged Charge ore replace batteries
Electric motor hums but does not
run Locked rotor (overload relay will
open after a period of time) Remove interference
Locked compressor Repair compressor
Defective clutch on engine (locked
up) Repair or replace clutch
Low line voltage or no voltage on
one leg Bring voltage up to within 10% of
motor rating
Contact chatter Low battery voltage Check voltage condition. Check
momentary voltage dip during
starting—low voltage prevents
magnet sealing
Defective or incorrect coil Replace coil
Poor contact in control circuit Check auxiliary switch contacts and
overload relay contacts. Check for
loose connections in control circuits
Poor ground on PC board Test ground circuit on PC board
Defective thermostat relay Check operation of thermostat relay