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March 26, 2019


Most homeowners don’t need to know every part of an air conditioner, but you should learn about the contactor if you like doing minor repairs or maintenance tasks on your own. For instance, replacing an air conditioning contactor is probably one of the easiest tasks for anyone with decent DIY skills.

But what is an AC contactor?
A contactor is like a switch that communicates with the thermostat and powers the fan and the compressor. It blocks or allows electricity to flow into the condenser, compressor, and motors. Think of it like a drawbridge that allows or hinders the passage of people into a castle. When the bridge is up, you have to wait until it is lowered down so that you can pass. Similarly, when you turn off the AC, the contactors are up, hence blocking the flow of electricity.

How does an AC contactor work with the thermostat?
The thermostat controls your air conditioner’s cooling cycles by communicating with the contactor. When your thermostat wants to cool your warm room, it sends a signal to the contactors. The tiny voltage is enough to lower the contactors, thus connecting them to the rest of the system. Your AC runs and starts sending cool air into your room. Once the desired temperature is achieved, the thermostat sends another signal to the contactors. The drawbridges elevate, and the flow of electricity is blocked.

Okay, so what causes the contactors to fail?
Friction eventually erodes the carbon layers of the contactor surface with frequent use. Once your contactor starts failing, your unit will also start to hum, click, or, worse, rumble. Nonetheless, a noisy air conditioner isn’t always due to worn contactors. This is why it’s a wise idea to contact a Maui air conditioning technician if you hear weird noises in your AC unit.

Replacing an air conditioning contactor
If you’re sure that the contactors are worn, replacing them is the rational option. You can do this job on your own if you have the right set of tools and skills. You will need a voltmeter, a screwdriver, needle-nose pliers, and wire strippers.

What’s the right replacement contactor?
Get a good look at your old contactor, because the replacement should look similar. The control voltage rating and amperage must be accurate. The poles and terminals should be the same as those on the old contactor.

How should you replace your contactor?
Replacing an air conditioning contactor is an easy task. That’s why I don’t mind telling clients with decent DIY skills to do it on their own.

Here are the steps in replacing an air conditioning contactor:
1. Turn off the power to your HVAC system. You may use a multimeter to make sure no power is
flowing into the system.
2. Identify the location of the wires on the contactor. Remove the wires.
3. Unfasten the mounting screws.
4. Set the replacement contactor in place and then reattach the wires tightly.
5. Turn the power back on. Observe the cooling cycles.

If your system is running smoothly and you don’t notice any problem, you’re good. But if replacing an air conditioning contactor doesn’t fix the problems, call us at 808-244-0161. We at Pacific Air Conditioning will fix your air conditioner on Maui any time of the day.







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