5-3
T-296
CONDITION
POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION
5.6 UNIT WILL NOT DEFROST PROPERLY --Continued
Frequent defrost
Wet load
Normal
5.7 ABNORMAL PRESSURES (COOLING)
Condenser coil dirty
6.10
Condenser fan rotating backwards
6.11
Condenser fan inoperative
6.11
High discharge pressure
Refrigerant overcharge or noncondensibles
6.7.1
High discharge pressure
Discharge pressure regulator valve defective
Replace
Discharge service valve partially closed
Open
Suction modulation valve malfunction
6.18
Suction service valve partially closed
Open
Filter-drier partially plugged
6.13
Low refrigerant charge
6.7.1
Expansion valve defective
6.14
Low suction pressure
No evaporator air flow or restricted air flow
6.15
Low suction pressure
Excessive frost on evaporator coil
5.6
Evaporator fan(s) rotating backwards
6.16.3
Discharge pressure regulator valve defective
Replace
Suction modulation valve malfunction
6.18
Suction and discharge pres-
Heat exchanger defective
Replace
Suction and discharge pres-
sures tend to equalize when unit
i
ti
Compressor valves defective
6.8
q
is operating
Compressor cycling/stopped
Check
5.8 ABNORMAL NOISE OR VIBRATIONS
Loose mounting bolts
Tighten
Worn bearings
6.8
Compressor
Worn or broken valves
6.8
Compressor
Liquid slugging
6.14
Insufficient oil
6.8.6
Bent, loose or striking venturi
Check
Condenser or Evaporator Fan
Worn motor bearings
6.11/6.16
Condenser or Evaporator Fan
Bent motor shaft
6.11/6.16
5.9 CONTROLLER MALFUNCTION
Defective Sensor
6.21
Will not control
Defective wiring
Check
Will not control
Fuse (F1, F2) blown
Replace
Stepper motor suction modulation valve circuit malfunction
6.18
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