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SECTION 5
5-3 T-268-07
CONDITION
POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION
5.7 ABNORMAL PRESSURES (COOLING)
High discharge pressure
Condenser coil dirty
Condenser fan rotating backwards
Condenser fan inoperative
Refrigerant overcharge or noncondensibles
Discharge pressure regulator valve defective
Discharge service valve partially closed
Perishable set point
Suction modulation valve (SMV) malfunction
6.17
6.18
6.18
6.6
Replace
Open
Normal
6.25
Low suction pressure
Suction service valve partially closed
Filter-drier partially plugged
Low refrigerant charge
Expansion valve defective
No evaporator air flow or restricted air flow
Excessive frost on evaporator coil
Evaporator fan(s) rotating backwards
Discharge pressure regulator valve defective
Suction modulation valve (SMV) malfunction
Open
6.11
6.4/6.6
6.26
5.10
5.6
6.14/6.16
Replace
6.25
Suction and discharge pressures
tend to equalize when unit is
operating
Heat exchanger defective
Compressor valves defective
Compressor cycling/stopped
Replace
6.8
Check
5.8 ABNORMAL NOISE OR VIBRATIONS
Compressor
Loose mounting bolts
Worn bearings
Worn or broken valves
Liquid slugging Insufficient oil
Tighten
6.7
6.7
5.11
6.10
Condenser or Evaporator Fan
Bent, loose or striking venturi
Worn motor bearings
Bent motor shaft
Check
6.15/6.18
6.15/6.18
5.9 TEMPERATURE CONTROLLER MALFUNCTION
Will not control
Defective Sensor
Defective wiring
Fuse (F1, F2) blown
Suction modulation valve (SMV) circuit malfunction
6.23
Check
Replace
6.25
5.10 NO EVAPORATOR AIR FLOW OR RESTRICTED AIR FLOW
Evaporator coil blocked
Frost on coil
Dirty coil
5.6
6.13
No or partial evaporator air flow
Evaporator fan motor internal protector open
Evaporator fan motor(s) defective
Evaporator fan(s) loose or defective
Evaporator fan contactor defective
6.15
6.15/6.16
6.15
Replace