AC-Appliance Pros Do It Yourself Air Conditioning Trouble Shooting Chart WARNING: Disconnect all power to unit before servicing. Contactor may break only one side. Failure to shut off power can cause electrical shock resulting in personal injury or death. Symptom Possible Cause Remedy Unit will not run Power off or loose electrical connection Check for correct voltage at contactor in condensing unit Thermostat out of calibration-set too high Reset Defective contactor Check for 24 volts at contactor coil - replace if contacts are open Blown fuses Replace fuses Transformer defective Check wiring-replace transformer High pressure control open (if provided) Reset-also see high head pressure remedy - the high pressure control opens at 450 PSIG Outdoor fan runs, compressor doesn't Run or start capacitor defective Replace Start relay defective Replace Loose connection Check for correct voltage at compressor - check & tighten all connections Compressor stuck, grounded or open motor winding, open internal overload. Wait at least 2 hours for overload to reset. If still open, replace the compressor Low voltage condition Add start kit components Insufficient cooling Improperly sized unit Recalculate load Improper indoor airflow Check - should be approximately 400 CFM per ton Incorrect refrigerant charge Charge per procedure attached to unit service panel Air, non-condensibles or moisture in system Recover refrigerant, evacuate & recharge, add filter drier Compressor short cycles Incorrect voltage At compressor terminals, voltage must be ± 10 % of nameplate marking when unit is operating. Defective overload protector Replace - check for correct voltage Refrigerant undercharge Add refrigerant Registers sweat Low indoor airflow Increase speed of blower or reduce restriction - replace air filter High head-low vapor pressures Restriction in liquid line, expansion device or filter drier Remove or replace defective component Flow check piston size too small Change to correct size piston Incorrect capillary tubes Change coil assembly High head-high or normal vapor pressure - cooling mode Dirty outdoor coil Clean coil Refrigerant overcharge Correct system charge Outdoor fan not running Repair or replace Air or non-condensibles in system Recover refrigerant, evacuate & recharge Low head-high vapor pressures Flow check piston size too large Change to correct size piston Defective compressor valves  Replace compressor Incorrect capillary tubes Replace coil assembly Low vapor - cool compressor - iced indoor coil Low indoor airflow Increase speed of blower or reduce restriction - replace air filter Operating below 65°F outdoors Add low ambient kit Moisture in system Recover refrigerant - evacuate & recharge - add filter drier High vapor pressure Excessive load Recheck load calculation Defective compressor Replace Fluctuating head & vapor pressures TXV hunting Check TXV bulb clamp - check air distribution on coil - replace TXV Air or non-condensibles in system Recover refrigerant, evacuate & recharge Gurgle or pulsing noise at expansion device or liquid line Air or non-condensibles in system Recover refrigerant, evacuate & recharge If you don't know which firm to call, ask if the contractor is a member of the Air Conditioning Contractors of America (ACCA). consumers can call (972)247-5383 or 1-800-260-8041 to confirm the contractor is a member or to locate a contractor who subscribes to the organization's code or ethics. ©2007 AC-Appliance Pros All Rights Reserved 1701 North Greenville Ave. Suite 606 Richardson, Texas 75081 972-664-0055 TACL B00027067E

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