Carrier 69NT40-561-019, Operation And Service Manual

Page: 85 / 136

6–5 T-359
6.11 ELECTRONIC 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
Failed EEV Replace
6.12 COMPRESSOR OPERATING IN REVERSE
NOTE
The compressor may start in reverse for up to 10 seconds to determine correct phase rotation if
required for phase detection.
CAUTION
!
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
CONDITION POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION