Addison RC/FC Series Installation Operation & Maintenance page 72

RC/FC Series Installation, Operation, and Maintenance Manual
Table 14.3: Refrigeration Circuit, Cont.
Problem
Compressor
Short Cycles
Running Cycle Too
Long Or Unit
Operates Continuously
Supply Air Temperature
Too High
Supply Air Temperature
Too Low
Blower Motor
Not Running
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Probable Cause
Thermostat location or malfunction
Improper refrigerant charge
Defective high or low pressure control
Cycling on internal overload
Defective expansion valve
Poor air distribution
High discharge pressure
Leaking discharge valves in compressor
Refrigerant undercharged
Dirty filter or evaporator coil
Dirty or clogged condensing unit coil
Air or other non-condensables in system
Defective compressor
Restriction in suction and liquid line
Control contacts stuck
Refrigerant undercharge or leak in system
Evaporator plugged with dirt or ice
Improperly adjusted or defective expansion
valve
Defective compressor
High discharge pressure
Airflow is too high
Airflow is too low
Return air temperature too low
Improper wiring
Defective motor
Defective thermostat or control circuit
Motor off on overload protector
Solution
Check thermostat, check heat
anticipator setting
Check subcooling, verify superheat
Check high or low pressure switch
Possible tight bearings – see above
Check TXV and superheat
Check ductwork for recirculation
See above – high discharge pressure
See above – high suction pressure
Check subcooling
Check filter, coil and airflow
Check coil and airflow
Check equalized high side pressure with
equivalent outdoor temperature
See above – high suction pressure
Check for restrictions in refrigerant circuit
Check thermostat, shorts in wiring, slave
relay compressor contactor
Check subcooling and check for leaks
Check evaporator, airflow and filter
Check superheat and adjust TXV,
check bulb
Check compressor for proper operation
See above- high discharge pressure
Check external static pressure
Check evaporator coil, filter, check for
closed dampers, grills, drive for loose parts,
belts, misalignment, check external
static pressure
Check entering air wet bulb conditions
Check wiring diagram
Check motor controller
Check "R" and "G" Circuit
Allow motor to cool, check amperage