AC Contactor Failure Symptoms

AC Contactor Failure Symptoms

Depending on what climate you live in, you probably use your AC almost every day. This is why it can be very frustrating when your AC isn’t working correctly. The thing about your AC is that troubleshooting it yourself is not easy. If you have some experience, there are a few things that you can take care of yourself.

But, if you aren’t well-versed in fixing things, then you might want to call a professional technician. Either way, you can learn a bit about your AC if you want to be more understanding and better at fixing it. Here’s more information about the contactor and what the symptoms of its failure are.

What Does the Contactor on an Air Conditioner Do?

The contactor of the air conditioner unit is the electrical transmitter or relay. This means it regulates the flow of electricity to various parts of the air conditioner. The contactor will send the current to the condenser and the outdoor fan motor to supply it with the energy needed to keep running. Essentially the contactor’s job is to allow and prevent power from getting into the AC unit in any way that it can. Now that you know what it does, you can probably see that it’s a pretty important part of your air conditioner unit.

Essentially an electrically controlled switch that’s used for switching an electrical power circuit on. Usually contactors are controlled by a low-level power circuit, not a switch circuit. Every time that you turn on the air conditioner, the contactor is lowered and electricity is allowed to power the system. When your home reaches the temperature that you set on the AC, the contactor will go up again and it’ll turn off.

How Does it Work?

Now, you probably need to know how this important part of your air conditioner works.

What happens is that while light switches need you to physically flip on the switch and pressure switches to operate, your contactor is triggered by a stolen. The solenoid pushes on a small plunger which is the button. There are cool Wendy’s in the part that is referred to as the coil and when the 24 volts hit it, it can generate enough force to pull down that button on top of the contactor. This is the drawbridge which closes and allows electricity to pass through and run the condenser fan and compressor in your air conditioner.

To get more in depth, the thermostat will sense that it’s warmer, than the temperature that you chose. If the temperature rises, so does the little switch inside of the stop making the proper 24 volt connection that you want. There’s a 24 volt connection that goes to the furnace control board to tell it to turn on the fan.

Also, the furnace will relay the message through the 24 volt signal to the 24 volt coil in a contactor. That coil will energize and pull down the button on the contactor. Once contact was made on both sides of it, but power can then pass on to the motor and compressor. This will give you the cool air that you need in your house.

Now that you know how it works, here are some symptoms of its failure that you might need to recognize.

AC Contactor Failure Symptoms

There are many signs that your AC contactor is failing. Usually, one of the easiest ways to tell is when you start hearing abnormal noises. When the contactor begins to fail, it won’t pull close. This means the connection between the two sides is unable to happen. Your thermostat might click on, but your AC unit won’t operate. This means the contactor is broken and isn’t giving any electrical current that it needs to run your system. If your contact is faulty or just failing completely, there are signs to realize this when it’s happening.

The first sign is humming. When your AC is on, you’ll hear a humming sound, but if the contactor fails, you will hear the sound, but the AC won’t power on. This could also be indicating that you have weak coils or dirty contacts that you’ll need to replace. This is caused by the button not being pushed in. If you want to try manually pressing the button, your unit will function like normal, but this can be very dangerous to do on your own, so you should not do that.

The next sound you want to keep in mind is chattering. If the contacts are dirty or the coil is weak, then you’ll hear the plunger in the AC make a chattering sound. This is because the plunger is trying to make contact but it can’t do so completely. Sometimes, if you replace the coils you can fix this issue, but you should always call an HVAC technician to resolve an issue like this one so that everything is fixed correctly and you aren’t hurt.

Sometimes your contactor can even overheat, and this will cause it to melt the plastic molding or casing around it. You’ll need to contact an HVAC technician immediately to be replaced, and you should turn off your AC unit. Don’t use your AC unit until this is fixed.

Testing AC Contactor

If you want to test if there’s something wrong with your AC contactor, then you can easily do it yourself. What you need is a screwdriver, a multimeter (View on Amazon), and a phone or camera.

1. First you need to turn off the power of your AC unit. Shut it down completely at the thermostat and at the breaker. This will decrease the chance of you getting electrocuted.

2. Then you’ll need to unscrew the side cover of the AC unit. Walk over to the unit and use your screwdriver to remove the side cover. You should be able to see the contactor and the corresponding wires after this.

3. Take a picture. You’ll need to remember where each wire was connected and how they’re positioned. Take a picture using your phone or camera to make sure that you can have it for later. Take different angles if you think you’ll need them.

4. Remove the contactor in the wires. Use the screwdriver to remove the contactor from the evening. Once the contactor has been removed, you can unplug all of the wires.

5. Test a contactor that you removed. Set your multimeter to the OL setting for it to work. Connect a multimeter to one of the volt terminals on both sides of it. If a contactor is working correctly, then you should see a reading on the multimeter between 5 and 20 volts. If you get a lower reading or no reading from your contacts, you’ll need to replace them immediately.

6. You can begin preparing to replace the contactor. You’ll have to purchase a manufacturer approved contactor. After you’ve purchased one you can replace it yourself or call a technician to do it. If you purchased one yourself and you want to replace it on your own, you can use the picture you took to rewire the new contactor correctly. Once you’re done, reinstall the condenser side cover and you’ll be all set to power on your AC unit.

Now that you know more about your contactor, you know more about how your AC unit works. You can use this information to either replace the contactor yourself or call a professional to do it for you.

Either way this is a great way to get your AC unit working again so that you can go back to being as cool as you want to indoors.

How to Fix AC Contractor

If you’re always having problems with your AC, you need to know what’s causing the issue and if you’ll need to get the AC repaired or replaced. Having a working AC is crucial for any home and fixing it is just one form of home improvement but there are many more.

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