5
−
3
T-364
CONDITION
POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION
5.6 UNIT WILL NOT DEFROST PROPERLY (Continued)
Initiates but does not defrost
Heater contactor or coil defective
Replace
Heater(s) burned out
Frequent defrost
Wet load
Normal
5.7 ABNORMAL PRESSURES
High discharge pressure
Condenser coil dirty
Condenser fan rotating backwards
Condenser fan inoperative
Refrigerant overcharge or noncondensibles
Discharge service valve partially closed
Open
Electronic expansion valve (EEV) control malfunction
Replace
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
Low refrigerant charge
No evaporator air flow or restricted air flow
Excessive frost on evaporator coil
Evaporator fan(s) rotating backwards
EEV control malfunction
Replace
Failed digital unloader valve (DUV)
Replace
Suction and discharge pres-
sures tend to equalize when unit
is operating
Compressor operating in reverse
Compressor cycling/stopped
Check
Failed digital unloader valve (DUV)
Replace
5.8 ABNORMAL NOISE OR VIBRATIONS
Compressor
Compressor start up after an extended shutdown
Normal
Brief chattering when manually shut down
Compressor operating in reverse
Loose mounting bolts or worn resilient mounts
Tighten/Replace
Loose upper mounting
Liquid slugging
Condenser or Evaporator Fan
Bent, loose or striking venturi
Check
Worn motor bearings
Bent motor shaft
5.9 MICROPROCESSOR MALFUNCTION
Will not control
Incorrect software and/or controller configuration
Check
Defective sensor
Defective wiring
Check
Low refrigerant charge
Summary of Contents for 69NT40-561-201
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Page 108: ...7 2 T 364 Based on Drawing 62 11753 Figure 7 2 SCHEMATIC DIAGRAM ...
Page 109: ...7 3 T 364 Based on Drawing 62 11753 Figure 7 3 UNIT WIRING DIAGRAM Sheet 1 of 2 ...
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