How Do You Know If The Contactor In Your Air Conditioning System Has Failed?
The AC contactor is a tiny, simple component in your outdoor air conditioning system. Despite its small size, it's vital for making sure your air conditioner runs correctly. The AC contactor is the bridge that transmits electricity from your home to the outdoor air conditioning unit.
The AC contactor consists of a metal coil and plunger in a small plastic box. When your thermostat turns your air conditioner on, it will send a small electric surge to the AC contactor, which will extend to create a circuit between the electricity in your home and your air conditioning system. When your home reaches your desired temperature and the thermostat turns the air conditioner off, it sends another electrical surge to the AC contactor, causing it to retract and stopping the flow of electricity to your air conditioner.
Since the AC contactor is made from metal, it's vulnerable to corrosion. It can also overheat since it carries large amounts of electricity to your air conditioner. An old AC contactor may fail after being subjected to heat and corrosion, causing your air conditioner to not work properly anymore. If there's something wrong with your home's air conditioner, read on to learn if the problem may be caused by a bad AC contactor.
Your Air Conditioner Won't Start or It Stays on All the Time
When an AC contactor fails, it may never extend when it receives a signal from your thermostat. Your air conditioner won't start since it's not able to receive any electricity. On the other hand, a bad AC contactor can also become stuck in the extended position and fail to retract when the thermostat tries to shut your air conditioning off. Your air conditioner will constantly receive power through the contactor, so it will always run.
Your Outdoor Unit Makes a Buzzing Noise
When an AC contactor operates normally, you'll hear a click from the electrical panel on your outdoor air conditioning unit when the thermostat turns your air conditioner on. The clicking sound is from the AC contactor extending. You'll hear another click when it retracts and your air conditioner turns off.
If the AC contactor is stuck, you'll hear a buzzing noise coming from the electrical panel instead of a clicking noise. That's caused by the contactor trying to repeatedly extend or retract without success.
The AC Contactor Is Charred
You can also visually examine the AC contactor to see if it's in good condition. After turning off power to your air conditioner, open the electrical panel on the unit and look for a small rectangular box. If the box or the contactor inside is scorched, your contactor most likely failed because of repeated arc faults.
When a contactor becomes corroded, it will sometimes generate arc faults when the power starts flowing through it. Arc faults are very hot, so they can cause the contactor to fail while making scorch marks on it.
If you think that your AC contactor is bad, call an air conditioning repair service in your area and have your unit inspected. An HVAC technician can test the contactor to see if it's still capable of carrying the electrical load that your air conditioner needs to function. If it's bad, the AC repair technician will disconnect it from the electrical wiring and replace it. With the contactor fixed, your thermostat will be able to turn your air conditioner on and off without any problems.