5-3
T-294-01
CONDITION
POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION
5.7 ABNORMAL PRESSURES (COOLING)
Condenser coil dirty
6.18
Condenser fan rotating backwards
6.19
Condenser fan inoperative
6.19
High discharge pressure
Refrigerant overcharge or noncondensibles
6.7
High discharge pressure
Discharge pressure regulator valve defective
Replace
Perishable set point
Normal
Stepper motor suction modulation valve (SMV) malfunction 6.24
Filter-drier partially plugged
6.12
Low refrigerant charge
6.5/6.7
Expansion valve defective
6.25
Low suction pressure
No evaporator air flow or restricted air flow
5.10
Low suction pressure
Excessive frost on evaporator coil
6.15/6.17
Evaporator fan(s) rotating backwards
6.15/6.17
Discharge pressure regulator valve defective
Replace
Stepper motor suction modulation valve (SMV) malfunction 6.24
Suction and discharge pressures
Heat exchanger defective
Replace
Suction and discharge pressures
tend to equalize when unit is
Compressor valves defective
6.9
q
operating
Compressor cycling/stopped
Check
5.8 ABNORMAL NOISE OR VIBRATIONS
Loose mounting bolts
Tighten
Compressor
Worn bearings
6.8
Compressor
Worn or broken valves
6.8
Liquid slugging
5.11
Bent, loose or striking venturi
Check
Condenser or Evaporator Fan
Worn motor bearings
6.16/6.19
Condenser or Evaporator Fan
Bent motor shaft
6.16/6.19
5.9 TEMPERATURE CONTROLLER MALFUNCTION
Defective Sensor
6.23
Defective wiring
Check
Will not control
Fuse (F1, F2) blown
Replace
Stepper motor suction modulation valve (SMV) circuit
malfunction
6.24
5.10 NO EVAPORATOR AIR FLOW OR RESTRICTED AIR FLOW
Evaporator coil blocked
Frost on coil
5.6
Evaporator coil blocked
Dirty coil
6.14
Evaporator fan motor internal protector (IP) open
6.16
No or partial evaporator air flow
Evaporator fan motor(s) (EM) defective
6.16/6.17
No or partial evaporator air flow
Evaporator fan(s) loose or defective
6.16
Evaporator fan contactor (EF or ES) defective
Replace
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