5-4
T-292
CONDITION
POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION
5.9 CONTROLLER MALFUNCTION
Defective Sensor
6.21
Defective wiring
Check
Will not control
Fuse (F1, F2, F3) blown
Replace
Will not control
Stepper motor suction modulation valve circuit malfunction
6.18
Low refrigerant charge
6.4
5.10 NO EVAPORATOR AIR FLOW OR RESTRICTED AIR FLOW
Evaporator coil blocked
Frost on coil
5.6
Evaporator coil blocked
Dirty coil
6.13
Evaporator fan motor internal protector open
6.15
No or partial evaporator air flow
Evaporator fan motor(s) defective
6.15
No or partial evaporator air flow
Evaporator fan(s) loose or defective
6.15
Evaporator fan contactor defective
Replace
5.11 THERMOSTATIC EXPANSION VALVE MALFUNCTION
Low refrigerant charge
6.4
External equalizer line plugged
Open
Wax, oil or dirt plugging valve or orifice Ice formation at
valve seat
6.12
Low suction pressure with high
superheat
Superheat not correct
6.12.1
superheat
Power assembly failure
Loss of element/bulb charge
6 12
Broken capillary
6.12
Foreign material in valve
Hi h
i
i h l
Superheat setting too low
6.12
High suction pressure with low
superheat
External equalizer line plugged Ice holding valve open
Open
superheat
Foreign material in valve
6.12
Liquid slugging in compressor
Pin and seat of expansion valve eroded or held open by
foreign material
6 12
Fluctuating suction pressure
Improper bulb location or installation
6.12
Fluctuating suction pressure
Low superheat setting
5.12 AUTOTRANSFORMER MALFUNCTION
Circuit breaker (CB-1 or CB-2) tripped
Check
Unit will not start
Autotransformer defective
6.19
Unit will not start
Power source not turned ON
Check
460 VAC power plug is not inserted into the receptacle
4.2.2
5.13 WATER-COOLED CONDENSER OR WATER PRESSURE SWITCH
High discharge pressure
Dirty coil
6 10
High discharge pressure
Noncondensibles
6.10
Condenser fan starts and stops
Water pressure switch malfunction
Check
Condenser fan starts and stops
Water supply interruption
Check
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Summary of Contents for 69NT40-531 Series
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