56T-305
CONDITION POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION
5.10 NO EVAPORATOR AIR FLOW OR RESTRICTED AIR FLOW
Evaporator coil blocked
Frost on coil 5.6, page 54
Dirty coil 6.15, page 70
No or partial evaporator air flow
Evaporator fan motor internal protector open 6.16, page 70
Evaporator fan motor(s) defective 6.16, page 70
Evaporator fan(s) loose or defective 6.16, page 70
Evaporator fan contactor defective Replace
5.11 THERMOSTATIC EXPANSION VALVE MALFUNCTION
Low suction pressure with high
superheat
Low refrigerant charge 6.7.1, page 60
External equalizer line plugged Open
Wax, oil or dirt plugging valve or orifice Ice formation at
valve seat
6.14, page 68
Superheat too high 6.7.1, page 60
Power assembly failure
6.14, page 68
Loss of element/bulb charge
Broken capillary
Foreign material in valve
High suction pressure with low
superheat
Superheat setting too low 6.14, page 68
External equalizer line plugged Ice holding valve open Open
Foreign material in valve 6.14, page 68
Liquid slugging in compressor
Pin and seat of expansion valve eroded or held open by
foreign material
6.14, page 68
Fluctuating suction pressure
Improper bulb location or installation
Low superheat setting
5.12 AUTOTRANSFORMER MALFUNCTION
Unit will not start
Circuit breaker (CB-1 or CB-2) tripped Check
Autotransformer defective 6.20, page 74
Power source not turned ON Check
460 VAC power plug is not inserted into the receptacle 4.2.2, page 45
5.13 WATER-COOLED CONDENSER OR WATER PRESSURE SWITCH
High discharge pressure
Dirty coil
6.12, page 67
Noncondensibles
Condenser fan starts and stops
Water pressure switch malfunction Check
Water supply interruption Check
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