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19 Cards in this Set
- Front
- Back
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Compressor and condensor fan motor will not start
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Power failure, Open disconnect switch, blown fuses or tripped circuit breaker, faulty wiring, loose terminals, contactor coil, protective interlock circuit contacts open, short cycle device not timed out.
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Compressor will not start but condensor fan will run
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Faulty wiring or loose connection, load side of contactor to compressor motor terminal, Run/Start capacitor, Start relay contacts stuck open, Open motor windings or overload.
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Condensor fan motor will not start
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Faulty wiring or loose connection, load side of contactor to condensor motor terminal, Run capacitor, Open condensor fan motor windings or overload, Bearings oversized.
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Compressor hums but will not start
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Faulty wiring, loose terminals, Compressor overload, Start relay, Run or start capacitor, defective compressor bearings, unequalized pressures on PSC motor, low line voltage, seized compressor.
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Compressor short cycles on low pressure
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Power failure, refrigerant charge low, low suction pressure, dirty TEV, defective TEV power element, TEV push rod packing loose, evaporator fins dirty or plugged, evaporator blower motor belt slipping, low evaporator air volume, dirty filters, restrictions.
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Compressor runs continuously - no cooling / inadequate cooling
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Primary or safety controls, defective compressor valves, refrigerant charge low, evaporator fins dirty or plugged, evaporator blower motor belt slipping, low evaporator air volume, dirty filters.
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Compressor runs continuously - cooling
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Faulty wiring, control circuit, thermostat set too low, excessive load in space.
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Compressor noisy
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Loose hold - down bolts, defective compressor bearings, defective compressor valves, compressor oil level.
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Compressor loses oil
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refrigerant charge low, very low suction pressure, oil trapped in system, compressor short cycling, low oil in system, refrigerant leak.
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Head pressure too high
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Overcharge of refrigerant, noncondesibles, condensor fans dirty or plugged, condensor fan belt slipping, inoperative condensor fan, wrong condensor fan rotation.
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Head pressure too low
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Refrigerant charge low, low suction pressure, condensor input air temperature low.
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Liquid line frosting or sweating
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Liquid valve partially closed, restrictions
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Suction pressure too high
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Defective compressor valves, high head pressure, noncondensibles
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Suction pressure too low
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Refrigerant charge low, evaporator belt slipping, evaporator fins dirty or plugged, low evaporator air flow, dirty filters.
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Suction line frosting or sweating
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Overcharge of refrigerant, TEV stuck open, Oversized TEV valve, evaporator fins dirty or plugged, evaporator belt slipping, dirty filters.
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Evaporator blower will not start
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Power failure, blown fuses or tripped circuit breaker, faulty wiring or loose terminals, control transformer, Evaporator fan relay coil or contacts, evaporator blower motor.
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Liquid refrigerant flooding back to compressor (TEV system)
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Superheat setting, loose thermal bulb, overcharge of refirgerant.
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Liquid refrigerant flooding back to the compressor (Cap tube system)
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Overcharge of refrigerant, high head pressure, excessive subcooling.
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Space temperature too high
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Thermostat, refrigerant charge low, low suction pressure, evaportor fins dirty or plugged, evaporato blower motor belt slipping, low evaporator air volume, dirty filters, ductwork small or restricted, thermostat setting too high, system too small for load.
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