6_Troubleshooting

Section 6

TROUBLESHOOTING

Condition	Possible Cause	Remedy / Reference
6.1Unit 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
Loss of control power	Circuit breaker OFF or defective	Check
	Control transformer defective	Replace
	Fuse (F3A/F3B) blown	Check
	Start-Stop switch OFF or defective	Check
Component(s) not operating	Evaporator fan motor internal protector open	7.10
	Condenser fan motor internal protector open	7.7
	Compressor internal protector open	7.4
	High pressure switch open	6.7
	Heat termination thermostat open	Replace
	Malfunction of current sensor	Replace
Compressor hums, but does not start	Low line voltage	Check
	Single phasing	Check
	Shorted or grounded motor windings	7.4
	Compressor seized	7.4
6.2Unit Operates Long or Continuously in Cooling
Container	Hot load	Normal
Container	Defective box insulation or air leak	Repair
Refrigeration system	Shortage of refrigerant	7.3
	Evaporator coil covered with ice	6.6
	Evaporator coil plugged with debris	7.9
	Evaporator fan(s) rotating backwards	7.9 / 7.10
	Air bypass around evaporator coil	Check
	Controller set too low	Reset
	Compressor service valves or liquid line shutoff valve partially closed	Open valves completely
	Dirty condenser	7.6
	Compressor worn	7.4
	Current limit (function code Cd32) set to wrong value	4.4.3
	Economizer solenoid valve malfunction	7.16
	Digital unloader valve stuck open	Replace
	Electronic expansion valve	Replace
6.3Unit Runs but has Insufficient Cooling
Refrigeration system	Abnormal pressures	6.7
	Abnormal temperatures	6.13
	Abnormal currents	6.14
	Controller malfunction	6.9
	Evaporator fan or motor defective	7.10
	Compressor service valves or liquid line shutoff valve partially closed	Open valves completely
	Frost on coil	6.10
	Digital unloader valve stuck open	Replace
	Electronic expansion valve	Replace
6.4Unit will not Heat or has Insufficient Heating
No operation of any kind	Start-Stop switch OFF or defective	Check
	Circuit breaker OFF or defective	Check
	External power source OFF	Turn ON
No control power	Circuit breaker or fuse defective	Replace
	Control Transformer defective	Replace
	Evaporator fan internal motor protector open	7.10
	Heat relay defective	Check
	Heater termination thermostat open	7.9
Unit will not heat or has insufficient heat	Heater(s) defective	7.9
	Heater contactor or coil defective	Replace
	Evaporator fan motor(s) defective or rotating backwards	7.9 / 7.10
	Evaporator fan motor contactor defective	Replace
	Controller malfunction	6.9
	Defective wiring	Replace
	Loose terminal connections	Tighten
	Low line voltage	3.3
6.5Unit will not Terminate Heating
Unit fails to stop heating	Controller improperly set	Reset
	Controller malfunction	6.9
	Heater termination thermostat remains closed along with the heat relay	7.9
6.6Unit will not Defrost Properly
Will not initiate defrost automatically	Defrost timer malfunction (Cd27)	Table 4–5
	Loose terminal connections	Tighten
	Defective wiring	Replace
	Defrost temperature sensor defective or heat termination thermostat open	Replace
	Heater contactor or coil defective	Replace
Will not initiate defrost manually	Manual defrost switch defective	Replace
	Keypad is defective	Replace
	Defrost temperature sensor open	Replace
Initiates but relay (DR) drops out	Low line voltage	3.3
Initiates but does not defrost	Heater contactor or coil defective	Replace
Initiates but does not defrost	Heater(s) burned out	7.9
Frequent defrost	Wet load	Normal
6.7Abnormal Pressures
High discharge pressure	Condenser coil dirty	7.6
	Condenser fan rotating backwards	7.7
	Condenser fan inoperative	7.7
	Refrigerant overcharge or non-condensibles	7.3
	Discharge service valve partially closed	Open
	Electronic expansion valve (EEV) control malfunction	Replace
Low suction pressure	Incorrect software and/or controller configuration	Check
	Failed suction pressure transducer (SPT) or evaporator pressure transducer (EPT)	Replace
	Suction service valve partially closed	Open
	Filter drier partially plugged	7.8
	Low refrigerant charge	7.3
	No evaporator air flow or restricted air flow	7.9
	Excessive frost on evaporator coil	6.6
	Evaporator fan(s) rotating backwards	7.10.3
	EEV control malfunction	Replace
	Failed digital unloader valve (DUV)	Replace
Suction and discharge pressures tend to equalize when unit is operating	Compressor operating in reverse	6.12
	Compressor cycling/stopped	Check
	Failed digital unloader valve (DUV)	Replace
6.8Abnormal Noise or Vibrations
Compressor	Compressor start up after an extended shutdown	Normal
	Brief chattering when manually shut down	Normal
	Compressor operating in reverse	6.12
	Loose mounting bolts or worn resilient mounts	Tighten/ Replace
	Loose upper mounting	7.4.1
	Liquid slugging	7.12
Condenser or Evaporator Fan	Bent, loose or striking venturi	Check
	Worn motor bearings	7.7 / 7.10
	Bent motor shaft	7.7 / 7.10
6.9Microprocessor Malfunction
Will not control	Incorrect software and/or controller configuration	Check
	Defective sensor	7.19
	Defective wiring	Check
	Low refrigerant charge	7.3
6.10No Evaporator Air Flow or Restricted Air Flow
Evaporator coil blocked	Frost on coil	6.6
Evaporator coil blocked	Dirty coil	7.9
No or partial evaporator air flow	Evaporator fan motor internal protector open	7.10
	Evaporator fan motor(s) defective	7.10
	Evaporator fan(s) loose or defective	7.10
	Evaporator fan contactor defective	Replace
6.11Electronic Expansion Valve Malfunction
Low suction pressure	Incorrect software and/or controller configuration	Check
	Failed suction pressure transducer (SPT), or evaporator pressure transducer (EPT)	Replace
	Suction service valve partially closed	Open
	Filter drier partially plugged	7.8
	Low refrigerant charge	7.3
	No evaporator air flow or restricted air flow	7.9
	Excessive frost on evaporator coil	6.6
	Evaporator fan(s) rotating backwards	7.10.3
	EEV control malfunction	6.11
	Failed digital unloader valve (DUV)	Replace
	Loose or insufficiently clamped sensor	Replace
High suction pressure with low superheat	Foreign material in valve	6.11
	Failed suction pressure transducer (SPT), or evaporator pressure transducer (EPT)	Replace
	EEV control malfunction	Replace
	Improperly seated powerhead	Ensure power head is locked and in place
Liquid slugging in compressor	Failed suction pressure transducer (SPT), or evaporator pressure transducer (EPT)	Replace
Liquid slugging in compressor	Failed EEV	Replace
6.12Compressor Operating in Reverse
The compressor may start in reverse for up to 10 seconds to determine correct phase rotation if required for phase detection. Allowing the scroll compressor to operate in reverse for more than two minutes will result in internal compressor damage. Turn the start-stop switch OFF immediately.

Electrical	Incorrect wiring of compressor	Check
	Incorrect wiring of compressor contactor(s)
	Incorrect wiring of current sensor
6.13Abnormal Temperatures
High discharge temperature	Condenser coil dirty	7.6
	Condenser fan rotating backwards	7.7
	Condenser fan inoperative	7.7
	Refrigerant overcharge or non-condensibles	7.3
	Discharge service valve partially closed	Open
	Electronic expansion valve (EEV) control malfunction	Replace
	Failed suction pressure transducer (SPT), or evaporator pressure transducer (EPT)	Replace
	Discharge temperature sensor drifting high	Replace
	Failed economizer expansion valve, economizer coil, or economizer solenoid valve	Replace
	Plugged economizer expansion valve, economizer coil, or economizer solenoid valve	Replace
	Loose or insufficiently clamped sensor	Replace
6.14Abnormal Currents
Unit reads abnormal currents	Current sensor wiring	Check