Common Air Conditioner Capacitor Failure Symptoms

Capacitor Failure Symptoms are sometime harder to identify without the right tools and expertise. Capacitors can be found in several different sizes and shapes. There may be one or multiple capacitors included in your ac with regards to the design. While the most popular capacitors are the types found on circuit boards, the ones most associated with air conditioning will be the bigger capacitors that assist start and run your motors. There are several motors present in an conditioner and heater systems:

  1. Compressor Motor Run Capacitor: Here is the most popular capacitor that fails. Most of the time these are duel capacitors, which means that there are 2 capacitors built into one. A duel capacitor will have three terminals on the top where a single capacitor will simply have two terminals on top.
  2. Outside Fan Motor Run Capacitor: That is the smaller capacitor found with or part of the Compressor Motor Capacitor. It helps start and run the outside fan that blows air through the outside coils.
  3. Indoor Blower Motor Run Capacitor: Similar to the outdoor fan motor capacitor, it is a small, single (two terminals) capacitor that will help start and run the indoor blower motor.
  4. Start Capacitor: Some models include an auxiliary start capacitor that helps jump start the motors. Most are found on the compressor. These are less common.

Why do capacitors go bad

When capacitors go south, they either go out entirely or they decline in strength. The decline is measured in the “capacitance” units called micro farads. When the capacitors are produced, they are labeled with their specifications capacitance and a range +/- from the design capacitance. This range is the allowable operating range, usually labeled in a percentage range, for the capacitor. If the capacitor starts to fail, the capacitance measured will be outside of the labeled range. Sometimes these are difficult to find any symptoms unless you have the proper tools. Warning, there is a risk of severe shock, so do not try this at home.

Diagnosing a bad capacitor

If a capacitor goes out completely, or is severely out of its operating range, it may prevent the motor affiliated with it from running completely. If the compressor motor is not working, then the air conditioner will not cool. If the outside fan is not working the compressor may cause problems and will short cycle or cease working. If the indoor fan stops, you’ll find that there is no air blowing through the vents.

For Quick, Honest and Affordable Service, call

Alexander Heating and Air Conditioning

1-919-886-HVAC (4822)

Raleigh Air Conditioner Repair

Holly Springs Air Conditioner Repair

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565 thoughts on “Common Air Conditioner Capacitor Failure Symptoms”

    1. Sorry, not enough info to give a definitive answer. Three most likely causes are a bad blower capacitor, a bad blower motor, a bad fan switch/circuit board.

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