Controller Malfunction; No Evaporator Air Flow Or Restricted Air Flow; Thermostatic Expansion Valve Malfunction; Autotransformer Malfunction - Carrier Streamline Scroll 69NT20-531-300 Operation & Service Manual

CONDITION

5.9 CONTROLLER MALFUNCTION

Will not control Will not control

5.10 NO EVAPORATOR AIR FLOW OR RESTRICTED AIR FLOW

Evaporator coil blocked Evaporator coil blocked
No or partial evaporator air flow No or partial evaporator air flow

5.11 THERMOSTATIC EXPANSION VALVE MALFUNCTION

Low suction pressure with high
superheat s perheat
Hi h High suction pressure with low i i h l
superheat superheat
Liquid slugging in compressor
Fluctuating suction pressure Fluctuating suction pressure

5.12 AUTOTRANSFORMER MALFUNCTION

Unit will not start Unit will not start

5.13 WATER-COOLED CONDENSER OR WATER PRESSURE SWITCH

Condenser fan starts and stops Condenser fan starts and stops
T-309
POSSIBLE CAUSE
Defective Sensor
Defective wiring
Fuse (F1, F2, F3) blown
Stepper motor suction modulation valve circuit malfunction 6.20
Low refrigerant charge
Frost on coil
Dirty coil
Evaporator fan motor internal protector open
Evaporator fan motor(s) defective
Evaporator fan(s) loose or defective
Evaporator fan contactor defective
Low refrigerant charge
External equalizer line plugged
Wax, oil or dirt plugging valve or orifice Ice formation at
valve seat
Superheat not correct
Power assembly failure
Loss of element/bulb charge
Broken capillary
Foreign material in valve
Superheat setting too low
External equalizer line plugged Ice holding valve open
Foreign material in valve
Pin and seat of expansion valve eroded or held open by for-
eign material
Improper bulb location or installation
Low superheat setting
Circuit breaker (CB-1 or CB-2) tripped
Power source not turned ON
Water pressure switch malfunction
Water supply interruption
5-4
REMEDY/
REFERENCE
SECTION
6.22
Check
Replace
6.7
5.6
6.15
6.17
6.17
6.17
Replace
6.7.1
Open
6.14
6.7.1
6.14 6 14
6.14
Open
6.14
6.14 6 14
Check
Check
Check
Check