SYMPTOMS POSSIBLE CAUSE CHECK OR REMEDIES
Short cycling of compressor (cont.) Low charge Check system charge
L
ow evaporator air flow Dirty coil
Dirty filter
Duct too small or restricted
Faulty run capacitor Replace
Faulty internal overload Replace compressor
Faulty Compressor Valves Fast equalization/ Replace compressor and examine
Low pressure difference system to locate reason
ELECTRICAL
SYMPTOMS POSSIBLE CAUSE CHECK OR REMEDIES
Voltage present on load side Compressor start components Check start capacitor
of compressor contactor and
compressor won’t run Check potential relay
Run capacitor Check with ohmmeter
Internal overload Allow time to reset
Compressor windings Check for correct ohms
Voltage present on line side of Thermostat Check for control voltage to com-
pressor contactor only contactor coil
Compressor control circuit High pressure switch
Low pressure switch
Ambient thermostat
Solid state protection control or
internal thermal sensors
Compressor timed off/on
control or interlock
No voltage on line side Blown fuses or tripped circuit breaker Check for short in wiring or unit
of compressor contactor
Improper wiring Re-check wiring diagram
Improper voltage High voltage Wrong unit
Power supply problem
Low voltage Wrong unit
Power supply problem
Wiring undersized
Loose connections
Single Phasing (3 phase) Check incoming power and fusing
CONTAMINATION
SYMPTOMS POSSIBLE CAUSE CHECK OR REMEDIES
Moisture Poor evacuation on installation In each case, the cure is the same.
or during service Recover refrigerant. Add filter drier,
evacuate and re-charge
High head pressure Non-condensibles air
Unusual head and suction readings Wrong refrigerant
Foreign Matter-
copper filings Copper tubing cuttings
Copper oxide Dirty copper piping
Welding scale Nitrogen not used
Soldering flux Adding flux before seating
copper part way
Excess soft solder Wrong solder material
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