Service manual

5-- 3
T -318
CONDITION POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION
5.6 UNIT WILL NOT DEFROST PROPERLY --Continued
Frequent defrost Wet load Normal
5.7 ABNORMAL PRESSURES (COOLING)
High discharge pressure
Condenser coil dirty 6.10
Condenser fan rotating backwards 6.11
Condenser fan inoperative 6.11
Refrigerant overcharge or noncondensibles 6.7.1
Discharge pressure regulator valve defective Replace
Discharge service valve partially closed Open
Suction modulation valve malfunction 6.18
Low suction pressure
Suction service valve partially closed Open
Filter-drier partially plugged 6.13
Low refrigerant charge 6.7.1
Expansion valve defective 6.14
No evaporator air flow or restricted air flow 6.15
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-
sures tend to equalize when unit
is operating
Heat exchanger defective Replace
Compressor valves defective 6.8
Compressor cycling/stopped Check
5.8 ABNORMAL NOISE OR VIBRATIONS
Compressor
Loose mounting bolts Tighten
Worn bearings 6.8
Worn or broken valves 6.8
Liquid slugging 6.14
Insufficient oil 6.8.6
Condenser or Evaporator Fan
Bent, loose or striking venturi Check
Worn motor bearings 6.11/6.16
Bent motor shaft 6.11/6.16
5.9 CONTROLLER MALFUNCTION
Will not control
Defective Sensor 6.22
Defective wiring Check
Fuse (F1, F2) blown Replace
Stepper motor suction modulation valve circuit malfunction 6.18