Even if you have a top-tier air conditioning unit, you should know how to find your air conditioning contactor. The AC contactor regulates the electrical connection between your home and the air conditioner. Your home provides the AC unit with power, but the contactor controls the flow of current to the rest of the AC hardware. The control switch then allows electrical energy to activate parts like the blower motor, condenser fan, and compressor.

The physical switch inside the condenser is the biggest issue after years of normal wear. That said, a lousy contactor might indicate an electrical failure elsewhere in your home or AC unit.


  • The contactor regulates the electrical energy between your home and the air conditioning hardware.
  • You can find the contactor underneath the electrical panel of your outdoor unit.
  • Always cut power to your AC unit before trying to diagnose a contactor failure.

A bad contactor is a severe mechanical failure or electrical issue that will stop your AC unit from working correctly. It can cause the electrical circuit to become overloaded and damage the device. Taking action quickly is necessary to prevent further damage to your system. Fortunately, most users can perform a contactor replacement without paying for maintenance. Before completing this air conditioning repair, we can show you where is the contactor on an air conditioner.

Performing periodic maintenance is critical for efficient operation regardless of the size of your air conditioner. Luckily, you do not need an AC technician for most problems. For example, you can check for mold in your air conditioner or locate the AC drain pan with a simple guide.

Insider Tip

A contactor failure is likely an electrical issue unless you see physical signs of damage or wear on the unit.

You can find the AC contactor in the outdoor unit under the electrical panel. Once you remove the panel, spotting an HVAC contactor is simple. The contactor is the leading electrical component that passes the electricity flow between your home and the AC unit. You should see a collection of power wires connected to the contactor.


You can suffer an electric shock by performing AC repairs while the unit is connected to power, so always make sure to turn off the power to your unit first.

One of the most unmistakable failure signs of a bad AC contactor is a loud chirping or humming sound from the condenser unit. You can also use a multimeter on the electrical contacts to diagnose an electric issue between the contactor and the AC unit.

In addition, check the physical condition of the contactor because damaged capacitors can prevent the proper flow of electricity in the unit. If you think a capacitor is faulty, we have a great guide on how to test an AC capacitor.

STAT: A 2020 US EIA (Energy Information Agency) survey shows that 88% of Americans use air conditioning equipment. (source)


How long does an AC contactor last?

You should get between 5 and 10 years out of a standard contactor. That said, you will get more life from your AC contactor with periodic maintenance and repair.

How do I test an AC contactor?

The most foolproof way to test an AC contactor is with a multimeter. Turn off power to the AC unit and remove the contactor from the condenser unit. Connect the multimeter to the low-volt terminals on the contactor, and you should see a reading between 5 and 20. If not, you have a bad AC contactor.

What happens when the air conditioning contactor goes bad?

If you have a contactor failure, the AC unit cannot manage your indoor temperature and may run nonstop, even when the thermostat is off. A bad contactor may also prevent the AC’s electrical system from activating, leading to a dead air conditioner.

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