Carrier VECTOR 1550 Series Operation & Service Manual page 260

INDICATION/
TROUBLE
10.4.9 Control System Malfunction
Will not control
10.4.10 No Evaporator Air Flow Or Restricted Air Flow
No or partial evaporator
air flow
Evaporator fan
10.4.11 Electronic Expansion Valve Malfunction
Low suction pressure
High suction pressure with low
superheat
Liquid slugging in compressor
62-61753-21
POSSIBLE CAUSES
Sensor defective
Relay(s) defective
Microprocessor controller malfunction
Check return air bulkhead and air chute. Ensure return air
is not restricted and chute is in good condition
Check coil for even air flow with no "dead" spots. Clean.
Frost on coil. To check defrost, run unit in cooling and
place in manual defrost.
Defrost air switch (DAS) defective or out of calibration
Evaporator blower loose or defective
Evaporator blower rotating backwards
Incorrect software and/or controller Configuration
Excessive frost on evaporator coil. Manually defrost.
Suction service valve partially closed
Filter drier partially plugged
Low refrigerant charge
No evaporator air flow or restricted air flow
Evaporator fans rotating backwards
Loose or insufficiently clamped suction temperature sen-
sor
Failed suction pressure transducer
Failed unloader valve
Electronic expansion valve malfunction
improperly seated power head
Failed suction pressure transducer
Foreign material in valve
Electronic expansion valve malfunction
Failed suction pressure transducer
Electronic expansion valve malfunction
10-8
REFERENCE
SECTION
8.7.7
Check
Check
Clean, repair or
replace.
8.6.2
3.9
8.6.13
8.7.2
8.7.2
Check
3.9
Open
8.6.5
8.5.4
8.6.2
8.7.2
Check
8.6.12
8.6.9
8.6.8
Ensure power
head is locked in
place
8.6.12
8.6.8
8.6.8
8.6.12
8.6.8