If your air conditioner isn’t turning on but you verified the AC has power from your circuit breaker, you may have a stuck relay. A stuck relay can cause your AC unit to suddenly break down in the Texas heat, so it’s important to fix it as soon as possible.  In this blog post, we will show you how to fix a stuck relay on an AC unit in Arlington, TX.

What Is A Relay And What Does It Do In An Ac Unit?

A relay is a switch that controls the flow of electricity to your air conditioner, allowing you to turn the air conditioner motor on and off, providing you with cold air when you need it. Your central AC, heat pump, and furnace all use an AC contactor or relay.

When the air conditioner is turned on, the relay closes and allows electricity to flow to the unit. 

When the air conditioner is turned off, the relay opens and interrupts the circuit, preventing electricity from flowing to the air conditioner. 

You can find the relay located in the outdoor unit of your HVAC system. Relays have three wires connected to them:

  • Input wire from the control board
  • Power feed wire to the ac compressor clutch
  • Ground wire 

The relay plays a large role in the energy efficiency of your air conditioner, depending on the type of relay and how well you’ve maintained your HVAC unit.

If the relay gets stuck in one position, it can prevent the air conditioner from turning on or cause it to turn off unexpectedly since the ac fan and blower motor won’t receive the necessary power to operate. A faulty relay is the main cause of electrical power problems with your HVAC unit. However, other factors could potentially be at play. For example, there may be a problem at the electronic control board or a damaged blower fan.

See the following video to learn more about why your condensing unit may be short cycling:

If you have warm air blowing from your central ac or an air flow problem or have noticed that your AC unit is freezing up, the problem probably lies somewhere else in your HVAC system. Ask a professional HVAC tech to help you diagnose the problem. 

How Do You Know If Your Relay Is Stuck And Needs To Be Fixed?

With all of the possible causes of AC system problems, how do you know if you have a stuck relay? Sings of AC relay failure include:

  • The air conditioner doesn’t turn on when you try to use it
  • The air conditioner turns off unexpectedly
  • You hear a clicking noise coming from the air conditioner
  • Visible damage or debris on the relay

If you notice any of these signs, you may want to test the relay with a multimeter for additional reassurance before completing the diagnostic stage.

A stuck relay will not start working properly again on its own. It will require repair or replacement. While we support homeowners learning about their HVAC system, consider hiring a professional air conditioner repair company when you have a stuck relay, especially considering it relates to your home’s electricity.  Don’t put yourself through an unnecessarily shocking and unsafe experience.

How To Fix A Stuck Relay On Your AC Unit

There are a few ways HVAC techs in Arlington, TX fix stuck relay:


If you do choose to take on the risk of repairing your air conditioner relay yourself (which we don’t recommend), always turn off power to the unit at the circuit breaker before you begin to work.

1. Clean the relay 

If the relay contacts get dirty, they can get stuck. Relays can get dirty thanks to dust, organic material, and other debris in the air outside. 

Remove the relay and clean the connectors gently with alcohol or vinegar and a rag. Before you clean the relay, apply masking tape over the wires to prevent damage. Do not oversaturate the relay with the alcohol, and thoroughly rinse off all remaining alcohol on the relay. Let the relay dry thoroughly before replacing it.

2. Replace the relay

If cleaning the relay didn’t work or you notice a damaged thermostat wire, you may need to replace the entire component. 

You will need to buy the exact replacement relay designed for your unit. Once you get the new part, you will remove the old relay and replace it in the same position as the new one. The old relay may have screws holding it in place so have your screwdriver later.

For more information on troubleshooting your HVAC relay, watch the following video:

If you have a stuck relay on your AC unit, contact All Masters for air conditioning repair in Arlington, TX today!

Tips For Preventing Your Relay From Becoming Stuck In The First Place

Prevent a problem before it happens using these simple tips on avoiding a stuck relay in your air conditioner unit.

1. Use your air conditioner sparingly

Excessive use of your air conditioner will cause your relay to get stuck. When in use, air conditioners generate heat. Too much heat may cause the relay material to essentially melt and stick together, causing them to become stuck.

To prevent the problem, be mindful not to keep the air conditioner running when not necessary. You may also want to invest in a programmable thermostat (also known as a smart thermostat) to automate the air conditioner, minimizing the possibility of human error.

2. Keep the outside unit clean

It’s impossible to prevent all debris from entering your outside unit. However, you can do your best to keep the area around it clean. Furthermore, cleaning the coils in your outside unit and replacing your HVAC system’s air filter should be part of your regular HVAC maintenance program that you perform once a year or every spring and fall. 

Cleaning the coils will prevent the relay from getting dirty, too.

Contact All Masters Plumbing for HVAC Repair in Arlington TX

If your air conditioner isn’t working properly or you think you may have a stuck relay, don’t hesitate to call All Masters Plumbing. We are a professional HVAC and AC repair company in Arlington TX that serves the entire DFW area. We would be happy to come out and take a look at your air conditioner and give you an estimate for the repairs.

Additional HVAC and plumbing services in Arlington include:

  • HVAC repair 
  • HVAC replacement
  • HVAC installation
  • Indoor air quality
  • Drain cleaning
  • Slab leak repair
  • Gas line repair

Unsure if we can help you? We provide repairs in the following service areas.

Faqs About Relays And AC Units

What is a relay?

A relay is a switch that controls the flow of electricity to the air conditioner. The relay is what turns the air conditioner on and off.

What does a stuck relay do?

If the relay gets stuck in one position, it can prevent the air conditioner from turning on or cause it to turn off unexpectedly.

Can I clean my own coils?

Yes, you can clean your own coils, but we recommend calling a professional HVAC repair company to do it for you.

Call Now ButtonClick to Schedule Now!