Photograph of client using tissue to look for air conditioning air flow Air Conditioning / Heat Pump Repair FAQ: How to Diagnose & Repair Air Conditioners & Heat Pumps

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This Air Conditioning Troubleshooting & Diagnosis FAQ (list of frequently asked questions about air conditioners) lists the major areas of investigation to be followed in diagnosing all types of problems with air conditioning systems and heat pump equipment.

Typical air conditioner concerns include compressor or blower assembly noises, failure of air conditioners to start or to keep running, inadequate cool air flow or air quantity, loss of air conditioner cooling capacity, reduced air conditioning output temperatures, loss of cool air supply, or even loss of air flow entirely.

Also discussed are various electrical wiring, fusing, overcurrent, and thermostat or control defects on air conditioners.

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Major Areas to Investigate for Problems With Air Conditioning Systems & Equipment

How to diagnose and fix an air conditioning system that is not working

Since the failure of an air conditioner to turn on, loss of air conditioner cooling capacity, reduced air conditioning output temperatures, loss of cool air supply, or even loss of air flow entirely can be due to a variety of problems with one or more components of an air conditioner or air conditioning system, after reviewing the lost air conditioner cooling diagnosis procedures described in this article, be sure to also review the diagnostic procedures at each of the individual air conditioning diagnosis and repair major topics listed just below. To return to our air conditioning and refrigeration home page go to AIR CONDITIONING & HEAT PUMP SYSTEMS.

If your air conditioning or heat pump system has lost its cooling capacity or won't start select one or more of the diagnostic articles listed below.

  • A/C - HEAT PUMP CONTROLS & SWITCHES: air conditioner controls and switches - begin here if your A/C won't start. Here's an important tip: most refrigeration problems, in air conditioners, refrigerators, or freezers, are electrical, not mechanical. In air conditioning school, we used to drive out and collect abandoned refrigerators that people were tossing out during our community's spring cleanup week. Taking these appliances back into the shop we found that almost always the problem that had caused the owner to dispose of their air conditioner or freezer was in an electrical connection or electrical control. So it's worth checking out switches and controls on an air conditioner before replacing more costly components.
  • OPERATING DEFECTS: major air conditioning problem symptoms and how to get the air conditioning system working again,e.g. compressor or fan noises, failure to start, and inadequate cool air volume
  • LOST COOLING CAPACITY: what to do when not enough cool air comes out of the system
  • COMPRESSOR CONDENSER: problems with air conditioner compressor/condenser units. Also see FAN, COMPRESSOR/CONDENSER UNIT for help in diagnosing and fixing problems with the outdoor compressor/condenser fan and fan motor.
  • AIR HANDLER UNIT: problems with the air handler, air filters, and the cooling coil itself
  • DUCT SYSTEM DEFECTS: problems with the air duct system, air filters, supply registers, return air registers
  • A/C REFRIGERANT LEAK DETECTION: how to use a TIF5000 to detect air conditioning refrigerant gas leak
  • A/C DIAGNOSTIC FAQs: air conditioning system diagnostic FAQs: Q&A about air conditioner repair


Continue reading at DIAGNOSTIC GUIDES A/C / HEAT PUMP or select a topic from the More Reading links shown below.

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REPAIR & DIAGNOSTIC FAQs for A/C at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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