6.12 Electronic Expansion Valve Malfunction; 6.13 Autotransformer Malfunction - Carrier 69NT40-561-399 Operation And Service Manual

6.12 ELECTRONIC EXPANSION VALVE MALFUNCTION

Condition
Low suction pressure
High suction pressure with low su-
perheat
Liquid slugging in compressor

6.13 AUTOTRANSFORMER MALFUNCTION

Condition
Unit will not start
T-365
Possible Cause
Incorrect software and/or controller configuration
Failed suction pressure transducer (SPT) or evaporator
pressure transducer (EPT)
Suction service valve partially closed
Filter drier partially plugged
Low refrigerant charge
No evaporator air flow or restricted air flow
Excessive frost on evaporator coil
Evaporator fan(s) rotating backwards
EEV control malfunction
Failed digital unloader valve (DUV)
Loose or insufficiently clamped sensor
Foreign material in valve
Failed suction pressure transducer (SPT) or evaporator
pressure transducer (EPT)
EEV control malfunction
Improperly seated powerhead
Failed suction pressure transducer (SPT) or evaporator
pressure transducer (EPT)
Failed EEV
Possible Cause
Circuit breaker (CB−1 or CB−2) tripped
Autotransformer defective
Power source not turned ON
460 VAC power plug is not inserted into the receptacle
6–6
Remedy/Refer-
ence Section
Check
Replace
Open
Section 7.12
Section 7.3
Section 7.8
Section 6.6
Section 7.14.3
Section 7.16
Replace
Replace
Section 7.16
Replace
Replace
Ensure power-
head is locked
and in place
Replace
Replace
Remedy/Refer-
ence Section
Check
Section 7.23
Check
Section 5.2.1