62-11848
6-4
Low suction pressure
Filter-drier partially plugged
Low refrigerant charge
Expansion valve malfunction
No evaporator air flow or restricted air flow
Excessive frost on coil
Check
Suction and discharge
pressures tend to equalize
when unit is operating
Compressor defective
Replace
Hot gas solenoid malfunction
Heating:
High discharge pressure
Overcharged system
Condenser fan or HP2 pressure switch defective
Non-condensables in system
Condenser motor/fan defective
Replace motor
Low discharge pressure
Compressor valve(s) worn or broken
Replace
Hot gas two-way valve malfunction
Low suction pressure
Low refrigerant charge
Compressor Pressure Regulating valve mis-adjusted
Condenser Pressure Regulating valve fault
6.2.7
Abnormal Noise
Compressor
Loose mounting bolts
Tighten
Worn bearings
Replace
Worn or broken valves
Replace
Liquid slugging
Insufficient oil
Check
Condenser or evaporator fan
Loose shroud
Check
Bearings defective
Check
Fan loose on shaft
Check
Bent shaft
6.2.8
Cab Command Malfunction
Cab Command non-operational
Fuse open
Replace
Microprocessor malfunction
Replace
Microprocessor/Cab Command cable
6.2.9
No Evaporator Air Flow or Restricted Air Flow
Evaporator coil blocked
Heavy frost on coil
Check
Coil dirty
No or partial evaporator air flow
Evaporator fan loose or defective
Check
Evaporator fan rotating backwards
Check
Evaporator air flow blocked in box
Check
Fan motor malfunction
Replace
Table 6–2 Mechanical Indications
INDICATION / TROUBLE
POSSIBLE CAUSES
REFERENCE
SECTION