MAINTENANCE WITH Q&A
Page 5-4
GENERAL TROUBLESHOOTING
PROBLEM PROBABLE CAUSE CORRECTIVE ACTION
Compressor will
not run
Conditioning system OFF Turn ON conditioning system
No electrical power Check facility circuit breaker
Wrong voltage applied to unit Check voltage and correct
Compressor internal overload tripped Will automatically reset when cooled
High/Low Limit tripped Correct cause of limit condition, repair and reset
Control alarm energized
Motor failure Check winding resistance and lead to ground
resistance
Motor shorted Replace compressor
Unit short
cycles
continuously
Gain setting too high Decrease gain setting
Proportional band setting to low Increase proportional band setting
Compressor low on refrigerant Check refrigerant and charge if necessary
Compressor
dif• cult to start
Wrong voltage applied to unit Connect correct voltage
Defective run/start capacitor(s) Replace capacitor(s)
Defective start relay Replace start relay
Refrigeration overcharge Recover and recharge
High load amps Low voltage Check supply circuit
Electrical malfunctions Check for proper wiring and correct compressor
capacitor
Check for grounds and measure winding resistance
Defective start relay Check and replace
Low Amps Low refrigerant Check for leaks; charge system
Insuf• cient
cooling effect
Refrigerant shortage Repair leak and recharge
Frosted coil Defrost and dry coil
Low air circulation Check fan blade and shaft. Blade may have come off
Exceeding rated live load capacity
(See data sheets)
Reduce live load
Cooling coils obstructed Remove obstruction or defrost
Clogged capillary tube Replace cap tube
Liquid Injection Solenoid valve bad,
(stuck open)
Replace valve
Dirty condenser Clean condenser
R-404A compressor frosting Possible leak in R-508B. Check ambient pressures
R-508B Head
Pressure too
high
Refrigerant overcharge Recover excess refrigerant
Exceeding rated live load capacity
(See data sheets)
Reduce live load
Air in system Recover, evacuate and recharge.
R-404A system short of gas Repair leak and recharge
Table 2. General Troubleshooting Procedures
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