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How Does A Bad A/C Contactor Sound Like?

What is an Air conditioner contactor? It is a device responsible for controlling the flow of electricity sent to your AC. Almost like a connecting drawbridge over a river, its lowering connects both sides, and when it goes up, no car can pass through. Similarly, a contract controls the flow of electricity by either blocking it or allowing it to flow to the AC’s condenser, compressor, and motors.

A bad AC contactor is much of a menace for the owner. When a contractor turns bad, fails, or breaks, it will not function, i.e., it won’t pull close. It is a forfeiture of connection between the two sides, not letting electricity flow through the AC system. In such a situation, an air conditioning service in Arcadia, CA, is recommended.

A Few Reasons For Faulty AC Contactor

  • The excess flow of current
  • Overvoltage
  • Continual chattering
  • Age-old parts
  • High temperature- no ventilation
  • Fluctuation of voltage and frequency- the impact of power quality
  • Corrosive environment- damaging chemicals
  • Excessive vibration and mechanical shock

Sounds Created By A Bad AC Contactor


1. Humming

When you switch on your AC, it makes a humming sound, but it doesn’t power on. The reasons could be:

  • It may be an indicator of weak coils or dirt collected on contacts. It is mainly caused due to the button not being pushed in; even though manually pushing in the button would do the trick, it may prove dangerous if you do it yourself.
  • It may be due to a defect in your AC’s contactor relay switch. This was designed to start the outdoor condenser unit and receive a signal from the air conditioner’s thermostat. Such an issue has to be resolved only by technicians and should never be ignored as they can cause massive damage to your system.

2. Chattering
When the contacts of your air conditioner are dirty, or it has a weak coil, when you switch on your AC, the plunger may make a chatter-like sound. Usually, replacing the coil does the trick but calling a technician is always the best option.

3. Buzzing

When the condenser unit of your AC starts buzzing, it is a sign to check it out. A bad contactor switch prevents power from flowing to the compressor. In this case, the power does flow through the contactor but doesn’t pass through it, and that causes the loud buzzing.

A thing to remember, you should not confuse soft humming noises that are very normal in air conditioners with constant humming caused by a bad contactor. This confusion will just cost you your money and time for no reason. AC contactors usually last for a long time, but regular maintenance is necessary for any electrical equipment.

If your AC conditioner goes bad, you need to get it replaced and serviced by an HVAC technician. And the best way to avoid this from happening altogether is to schedule regular tune-ups with your technician and service your air conditioner, replace and repair old and worn-out contractors on a routine basis.

For the best air conditioning company in Arcadia, contact AC Tech Inc. We ensure technical expertise and on-time service. Reach out to us at (626) 689-8068.