Troubleshooting

Section 6

TROUBLESHOOTING

6.1unit will not start or starts then stops
Condition	Possible Cause	Remedy / Reference Section
No power to unit	External power source OFF	Turn On
	Start−Stop switch OFF or defective	Check
	Circuit breaker tripped or OFF	Check
	Autotransformer not connected	Section 5.2.2
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	Section 7.14
	Condenser fan motor internal protector open	Section 7.8
	Compressor internal protector open	Section 7.8
	High pressure switch open	Section 6.7
	Heat termination thermostat open	Replace
	Malfunction of current sensor	Replace

6.2UNIT OPERATES LONG OR CONTINUOUSLY IN COOLING
Condition	Possible Cause	Remedy / Reference Section
Container	Hot load	Normal
Container	Defective box insulation or air leak	Repair
Refrigeration system	Shortage of refrigerant	Section 7.3
	Evaporator coil covered with ice	Section 6.6
	Evaporator coil plugged with debris	Section 7.13
	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	Section 7.10.1
	Compressor worn	Section 7.8
	Current limit (function code Cd32) set to wrong value	Section 4.4.3
	Economizer solenoid valve malfunction	Section 7.17
	Digital unloader valve stuck open	Section 7.21.1
	Electronic expansion valve	Section 7.16.1

6.3UNIT RUNS BUT HAS INSUFFICIENT COOLING
Condition	Possible Cause	Remedy / Reference Section
Refrigeration system	Abnormal pressures	Section 6.7
	Abnormal temperatures	Section 6.15
	Abnormal currents	Section 6.16
	Controller malfunction	Section 6.9
	Evaporator fan or motor defective	Section 7.14
	Compressor service valves or liquid line shutoff valve partially closed	Open valves completely
	Frost on coil	Section 6.10
	Digital unloader valve stuck open	Section 7.21.1
	Electronic expansion valve	Section 7.16.1

6.4UNIT WILL NOT HEAT OR HAS INSUFFICIENT HEATING
Condition	Possible Cause	Remedy / Reference Section
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	Section 7.14
	Heat relay defective	Check
	Heater termination thermostat open	Section 7.13
Unit will not heat or has insufficient heat	Heater(s) defective	Section 7.13
	Heater contactor or coil defective	Replace
	Evaporator fan motor(s) defective or running backwards	Section 7.13 / Section 7.14
	Evaporator fan motor contactor defective	Replace
	Controller malfunction	Section 6.9
	Defective wiring	Replace
	Loose terminal connections	Tighten
	Low line voltage	Section 3.3

6.5UNIT WILL NOT TERMINATE HEATING
Condition	Possible Cause	Remedy / Reference Section
Unit fails to stop heating	Controller improperly set	Reset
	Controller malfunction	Section 6.9
	Heater termination thermostat remains closed along with the heat relay	Section 7.13

6.6UNIT WILL NOT DEFROST PROPERLY
Condition	Possible Cause	Remedy / Reference Section
Will not initiate defrost automatically	Defrost timer malfunction (Cd27)	Section Table 4–3
	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	Keypad is defective	Replace
Will not initiate defrost manually	Defrost temperature sensor open	Replace
Initiates but relay (DR) drops out	Low Line Voltage	Section 3.3
Initiates but does not defrost	Heater contactor or coil defective	Replace
Initiates but does not defrost	Heater(s) burned out	Section 7.13

6.7ABNORMAL PRESSURES
Condition	Possible Cause	Remedy / Reference Section
High discharge pressure	Condenser coil dirty	Section 7.10.1
	Condenser fan rotating backwards	Section 7.10
	Condenser fan inoperative	Section 7.11
	Refrigerant overcharge or non-condensibles	Section 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	Section 7.12
	Low refrigerant charge	Section 7.3
	No evaporator air flow or restricted air flow	Section 7.13
	Excessive frost on evaporator coil	Section 6.6
	Evaporator fan(s) rotating backwards	Section 7.14.3
	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	Section 6.14
	Compressor cycling/stopped	Check
	Failed digital unloader valve (DUV)	Replace

6.8ABNORMAL NOISE OR VIBRATIONS
Condition	Possible Cause	Remedy / Reference Section
Compressor	Compressor start up after an extended shutdown	Normal
	Brief chattering when manually shut down	Normal
	Compressor operating in reverse	Section 6.14
	Loose mounting bolts or worn resilient mounts	Tighten/Replace
	Loose upper mounting	Section 7.8.1
	Liquid slugging	Section 7.13
Condenser or Evaporator Fan	Bent, loose or striking venturi	Check
	Worn motor bearings	Section 7.11 / Section 7.14
	Bent motor shaft	Section 7.11 / Section 7.14

6.9MICROPROCESSOR MALFUNCTION
Condition	Possible Cause	Remedy / Reference Section
Will not control	Incorrect software and/or controller configuration	Check
	Defective sensor	Section 7.24
	Defective wiring	Check
	Low refrigerant charge	Section 7.3

6.10NO EVAPORATOR AIR FLOW OR RESTRICTED AIR FLOW
Condition	Possible Cause	Remedy / Reference Section
Evaporator coil blocked	Frost on coil	Section 6.6
Evaporator coil blocked	Dirty coil	Section 7.13
No or partial evaporator air flow	Evaporator fan motor internal protector open	Section 7.14
	Evaporator fan motor(s) defective	Section 7.14
	Evaporator fan(s) loose or defective	Section 7.14
	Evaporator fan contactor defective	Replace

6.11EAUTOFRESH NOT OPERATING
Condition	Possible Cause	Remedy / Reference Section
Vent not opening	Unit not Configured for eAutoFresh Operation	No action
	Cd43 in Off mode	Section 5.4.2
	Wiring disconnected	Check wiring
	Stepper drive defective	Section 7.27.2
	Stepper motor defective	Section 7.27.4
	Unit operating in frozen mode	Section 5.4.3
Gas Limit mode unavailable	Check CO₂ sensor	Section 5.4.3
	Wiring disconnected	Check wiring
	Unit operating in frozen mode	Section 5.4.3
Unable to calibrate CO2 sensor	“Enter” Key not held for sufficient length of time	Section 5.4.3
	CO₂ outside of acceptable levels	Check
	Check CO₂ sensor	Section 5.4.3
Code 44 displays “-----”	Unit not Configured for eAutoFresh Operation	No action
Code 44 displays “-----”	Check CO₂ sensor	Section 5.4.3

6.12ELECTRONIC EXPANSION VALVE MALFUNCTION
Condition	Possible Cause	Remedy / Reference Section
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	Section 7.12
	Low refrigerant charge	Section 7.3
	No evaporator air flow or restricted air flow	Section 7.8
	Excessive frost on evaporator coil	Section 6.6
	Evaporator fan(s) rotating backwards	Section 7.14.3
	EEV control malfunction	Section 7.16
	Failed digital unloader valve (DUV)	Replace
	Loose or insufficiently clamped sensor	Replace
High suction pressure with low superheat	Foreign material in valve	Section 7.16
	Failed suction pressure transducer (SPT) or evaporator pressure transducer (EPT)	Replace
	EEV control malfunction	Replace
	Improperly seated powerhead	Ensure powerhead is locked and in place
Liquid slugging in compressor	Failed suction pressure transducer (SPT) or evaporator pressure transducer (EPT)	Replace
	Failed EEV	Replace

6.13Autotransformer malfunction
Condition	Possible Cause	Remedy / Reference Section
Unit will not start	Circuit breaker (CB−1 or CB−2) tripped	Check
	Autotransformer defective	Section 7.23
	Power source not turned ON	Check
	460 VAC power plug is not inserted into the receptacle	Section 5.2.1

6.14Compressor Operating in Reverse
Condition	Possible Cause	Remedy / Reference Section
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

6.15ABNORMAL TEMPERATURES
Condition	Possible Cause	Remedy / Reference Section
High discharge temperature	Gas Cooler coil dirty	Section 7.10.1
	Gas Cooler fan rotating backwards	Section 7.11
	Gas Cooler fan inoperative	Section 7.11.1
	Refrigerant overcharge or non-condensibles	Section 7.3
	Discharge service valve partially closed	Open
	Electronic expansion valve (EEV) control malfunction	Section 7.16.1
	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

6.16ABNORMAL CURRENTS
Condition	Possible Cause	Remedy / Reference Section
Unit reads abnormal currents	Current sensor wiring	Check