Thermo King T-500R Maintenance Manual page 266

Electric Standby (Optional) Diagnosis
Condition
Unit turned On—Microprocessor
display does not come on
Unit turned On—Microprocessor
display comes on but electric
motor does not run
Electric motor hums but does
not run
Possible Cause
Battery discharged
Faulty battery cable connections
Fuse F21 blown
Fuse F4blown
Fuse F1 blown
Fuse F2 blown
Open circuit
Faulty On/Off relay K4
No standby power
Diesel operation selected
Unit in NULL
Fuse F25 blown (Fuse F5 T-500R/
T-Dairy)
Faulty LPCO (T-500R/T-Dairy)
Faulty HPCO
Open or faulty overload relay
Faulty run relay K1 (K9 T-500R/
T-Dairy)
Faulty diesel/electric relay K5
Faulty phase select module
Faulty motor contactor
Open circuit
Faulty drive motor
Batteries discharged
Locked rotor (overload relay will
open after a period of time)
Locked compressor
Defective clutch on engine (locked
up)
Electric Standby Diagnosis
Remedy
Charge or replace battery
Clean battery cables
Check for short circuits and replace
fuse
Check for short circuits and replace
fuse
Check for short circuits and replace
fuse
Check for short circuits and replace
fuse
Check HMI Harness
Check On/Off relay K4
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
Select ELECTRIC
Check setpoint and box temperature
Check for short circuit and replace
fuse
Check LPCO
Check HPCO
Determine cause and reset or
replace overload relay
Check run relay K1
Check diesel/electric relay K5
Check phase select module
Check motor contactors
Check 8, ER, EOL, 7E, 7EA, 7EB,
7EC, CH, L1, L2, and L3 circuits
Check drive motor
Charge or replace batteries
Remove interference
Repair compressor
Repair or replace clutch
14-2