3-1
SECTION 3
TROUBLESHOOTING
INDICATION/
REFERENCE
TROUBLE
POSSIBLE CAUSES
SECTION
3.1 UNIT WILL NOT START OR STARTS THEN STOPS
No power to unit
External power source OFF
Turn on
Start-Stop switch OFF or defective
Check
Circuit breaker tripped or OFF
Check
Modular transformer not connected
4.22
Loss of control power
Circuit breaker OFF or defective
Check
Control transformer defective (TR)
Replace
Fuse blown (F3)
Check
Start-Stop switch OFF or defective
Check
Loss of control power in
Evaporator fan motor internal protector open
4.15
respective branch of
Condenser fan motor internal protector open
4.18
control circuit only
Compressor internal protector open
4.7
High pressure switch open
3.7
Heat termination thermostat (HTT) open
Replace
Compressor hums,
Low line voltage
Check
but does not start
Single phasing
Check
Shorted or grounded motor windings
4.7
Compressor seized
4.7
Voltage switch (VS) not wired properly
Check
3.2 UNIT RUNS BUT HAS INSUFFICIENT COOLING
Compressor
Compressor valves defective
4.7
Refrigeration System
Abnormal pressures
3.7
Temperature controller malfunction
3.9
Evaporator fan or motor defective
4.15
Suction modulation valve malfunction
4.25
Suction solenoid valve malfunction
1.10/4.24
3.3 UNIT OPERATES LONG OR CONTINUOUSLY IN COOLING
Container
Hot load
Normal
Defective box insulation or air leak
Repair
Refrigeration System
Shortage of refrigerant
4.4/4.6
Evaporator coil covered with ice
3.6
Evaporator coil plugged with debris
4.14
Evaporator fan(s) rotating backwards
4.15/4.27
Defective evaporator fan motor/capacitor
4.15/4.27
Air bypass around evaporator coil
Check
Controller set too low
Reset
Compressor service valves or liquid
Open valves
line shutoff valve partially closed
completely
Dirty condenser
4.17
Compressor worn
4.7
Current limit (Code 32) set to wrong value
1.12.5
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