An air conditioning unit consists of various components. There are bigger components like condenser coils, evaporator coils, the thermostat, and the compressor, but there are some smaller parts that are also important for the AC to work and one of them is a contactor. It is a comparatively inexpensive component, but if it fails and you have it replaced by an air conditioner repair service, your air conditioner may not work. So, you should know what it is and the tell-tale signs that you have to replace it.
What Is An AC Contactor?
An air conditioner contactor is a small device that controls the flow of electricity to the condenser unit (outdoor unit). Think it of like a light switch. Just like when you turn on the light switch, the switch allows power to the light fixture, and the room is illuminated. When you turn the wall switch off, it stops the flow of electrical current and the light fixture turns off.
A contactor also works like that, but it does it automatically and gets the signal to turn on or off from the thermostat. Moreover, its on and off is opening and closing, where closing means that it allows electricity to the unit and opening means that it’s guarding and not allowing electricity to the unit.
Therefore, in its standard position, the contactor is open. In the cooling mode, when the house is warm, the thermostat sends a signal to the contactor. The contactor then closes which allows the electrical current to reach the compressor and other parts for cooling the house. When the desired temperature is reached, the thermostat signals the contactor to close. Therefore, the contactor closes and the compressor turns off. This is the role of a contactor in cycling on and off an HVAC unit to keep the house cool.
Where Is The AC Contactor Located?
We mentioned above that a contactor is present in the condenser unit of an HVAC system. When you remove the access panel of the outdoor unit, you may see a small, black, rectangular device that has two wires connected at its one end and two wires at its other end. That’s the contactor. Make sure to never remove the access panel before turning off power to the unit.
Signs To Replace Your AC Contactor
The AC Won’t Turn On
An air conditioner not turning on could be due to various reasons. However, one of the reasons can be a failed contactor. So, finding the right cause of the problem is important. This should be done by an expert.
In case of a faulty contactor, it becomes stuck at the position that doesn’t allow current to the condenser unit. So, even when the thermostat is on and requires the condenser unit to start the compressor for cooling, the contactor won’t allow electricity so the compressor won’t turn on. This means there will be no cooling (or heating). In fact, the condenser unit will be lifeless because it won’t even receive power to run the fan inside the condenser unit let alone the compressor.
A Chattering Or Buzzing Noise
Unusual noises coming from the HVAC unit are also a sign of a problem. A noisy air conditioner hints at various problems. A Chattering or buzzing noise usually means that the AC unit is not receiving power properly and it isn’t working stably. This can cause overheating and damage to the components. Sometimes, the cause of this issue is a malfunctioning contactor.
When a contactor is worn, the contacts on it can’t create a stable electrical connection. This leads to intermittent power and the chattering or buzzing noises from the unit. You might also hear a rattling or similar noise mostly when the unit tries to turn on. Moreover, some experts also share that people hear a clicking noise coming from the unit even when the unit is not on. If you hear any of these noises, turn off the unit and consult an expert.
If the contactor is bad, the expert will usually recommend a replacement. You can also have it reset, but this will only fix the issue temporarily so it’s better to replace the contactor than to reset given that it’s not an expensive component.
The AC Runs Intermittently
We explained above why you may hear chattering or buzzing noises. They are when the contactor is malfunctioning and can’t provide a stable flow of electrical current. So, even if you don’t hear these noises but your HVAC runs intermittently, it may be because of a worn contactor.
Visual Damage
To check for visual damage, you will need to remove the casing of the condenser unit. We have mentioned earlier what a contactor looks like.
When a contactor appears damaged from the outside, it’s called pitting. This means the contactor has been exposed to high voltage and heat for longer periods. This affects the ability of the contactor to switch from the on and off position. It usually sticks at the open position due to which it doesn’t let any electrical flow to the condenser unit.
Charring
If the contactor is charring or sparking, it’s no longer offering a stable connection. You may also hear a sparking noise and intermittent AC functioning. This is not a good state for your air conditioner to run, so you should turn it off immediately and have an expert check for problems.
Testing An AC Contactor
When you notice these signs, you should consult a professional for repairs. However, if you have skills in this area, you can do it with care.
- Turn off the power to the air conditioner by switching the breaker off.
- Wear protective gloves to prevent an electric shock.
- Reach the condenser unit and remove its side cover. You may need a screwdriver for this.
- Look for a black, rectangular device that’s fixed near a gray cylindrical device.
- Make sure to not touch the cylindrical device. It’s the capacitor and it holds charge even when the AC is not receiving power.
- Take a picture of that area so you know in which sequence the wires were connected.
- Carefully remove the wires from the contactor and unscrew it to remove it from the condenser unit.
- Take out your multimeter and set it to OL.
- Now, connect the terminals of the multimeter to the ends of the contactor.
- Check the reading. If the reading is between 5 to 20, the contactor is fine. But if you notice the reading to be anything lower than 5, the contactor is faulty.
- If the contactor is faulty, you should take it to the hardware store where you can buy the exact replacement.
- After getting the replacement, use the picture you took to carefully fit the contactor back.
- Put the condenser unit’s side cover back its place as well.
Conclusion
A faulty contactor can cause problems like ineffective cooling or the compressor not turning on. So, if notice any signs mentioned above, you should consult AC repair services Chantilly. An expert will inspect your HVAC unit and suggest if you need to replace the contactor or any other part of the unit.
