Carrier 69NT40-561-300, Operation And Service Manual

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T-365 6–6
6.12 ELECTRONIC EXPANSION VALVE MALFUNCTION
Condition Possible Cause Remedy/Refer-
ence 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 su-
perheat
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 power-
head is locked
and in place
Liquid slugging in compressor Failed suction pressure transducer (SPT) or evaporator
pressure transducer (EPT) Replace
Failed EEV Replace
6.13 AUTOTRANSFORMER MALFUNCTION
Condition Possible Cause Remedy/Refer-
ence 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