49
Compressor loses oil
Shortage of refrigerant
Repair leak and recharge
Plugged expansion valve
Clean expansion valve
Wrong oil viscosity
Use proper oil
Short cycling
Refer to “unit short cycling”
Frosted or sweating suction
Expansion valve set too low,
admitting excess refrigerant
Adjust expansion valve
Hot liquid line
Shortage of refrigerant
Repair leak and recharge
Condenser fan not running
Check fan motor
Dirty condenser coil
Clean condenser
Frosted liquid line
Restricted dryer
Replace
Condenser coil is cool when
unit is in cooling mode
Refrigerant undercharge
Repair leak and recharge
Compressor inefficient
Replace compressor
Unit cools in defrost cycle
Hot gas solenoid valve stuck
open
Loose or broken electrical
connections
Unit in vacuum. Frost
expansion valve only
Ice plugging expansion valve
Apply hot wet cloth to expansion
valve. Moisture indicated by
increase in suction pressure.
Replace dryer
Plugged expansion valve
Clean expansion valve
Expansion valve bulb
Replace expansion valve
Electric standby service
checks
Motor not running
Check for power at source and
work your way to the motors
Power at motor terminals but
motor not running
Check capacitors and motor
windings
Motor hums but doesn’t run
Check for locked motor
Check for worn bearings. Replace if
necessary
Check for locked compressor and
repair
Check power source for single
phasing (on three phase units)
Check start relay
Check Transformer
Check for power output
Check rectifier
Check for rectifier output
