How Will You Know If Your AC Contactor Is Failing?

When your air conditioning system is not performing optimally, it can be easy to overlook the role of the AC contactor switch. Although most people will usually look at the compressor or refrigerant levels to find out why their unit isn't working as well as they should, if the Ac Contactor Switch is not functioning properly, it may cause issues with other components of your air conditioning system.

In this article, learn more about the functions of an AC contactor switch, identify signs that it is failing and troubleshoot the issue successfully.

What Is an AC Contact Switch?

Also known simply as a "contactor," this device controls the flow of electricity to the main components of your air conditioning system. It connects the high-voltage power source to the compressor and fan motor based on signals from the thermostat. When you turn on the AC, the contactor receives the thermostat signal and starts the compressor and fan motor. The contactor has two or more metal contacts that close to complete the circuit. With frequent use, these contacts wear out and eventually stop working properly.

Where Is an AC Contact Stored?

You will find your AC contactor switch located inside your outdoor condenser unit. It is responsible for regulating the electrical supply to your compressor and fan. If you take off the outer cover of the condenser unit, you should see it mounted on a terminal strip that is close to other electrical parts. The AC contactor resembles a small black box with wires attached to it.

Signs Your AC Contactor Is Failing

If your AC contactor is failing, you may experience the following symptoms:

• Your AC unit will not turn on: A faulty contactor will prevent the system from turning on, and you will sweat it out until someone can repair it.
• Buzzing or humming noises: A bad contactor will create odd electrical sounds due to broken coil connections or worn-out contacts.
• Intermittent cooling: If your AC system is turning on and off sporadically, the contactor is not making a solid electrical connection.
• Burned or discolored components: After examination of the contactor, you may witness signs of burning or discoloration around the contactor meaning it has overheated or has undergone some electrical stress.

Finding these signs early can assist in preventing additional damage to your AC unit and can save you from costly repair bills.

What Does the AC Contactor Do?

The AC contactor is essential to the operation of your air conditioning system. When your thermostat indicates that cooling is needed, the contactor closes its metal contacts which allows high-voltage electricity to flow to the compressor and fan motor, causing your air conditioning system to operate and to cool the inside of your home. After your desired level of temperature has been reached via the thermostat, the contactor will open its contacts, and cut off the power supply to the AC unit, therefore putting your unit in standby mode.

How to Troubleshoot and Test Your AC Contactors

If you suspect an issue with your contactor, follow these steps to test and troubleshoot:

1. Disconnect Power Supply: Make sure to cut off power from the AC unit (turn off all switches) before doing any of the tests. Prioritize safety by ensuring the power is off.
2. Inspect Contactors Physically: Look for damage or charred appearance on the contactors; if there are signs of either, then it's possible that they need replacing.
3. Use a Multimeter: Set the multimeter to measure voltage. Connect the probes across the line terminal and load terminal. If your results show inconsistencies, it's likely caused by faulty contactors.
4. Listen for Sounds: If you hear buzzing or clicking sounds every time the thermostat sends a signal, these noises indicate possible damage or failure of the coil, suggesting that the contacts cannot hold a proper connection any longer.

If you suspect a contactor problem, don't delay; take immediate action. The quicker you address the issue, the less likely you are to experience further complications such as damages in your AC unit or safety hazards like electrical fires.

How Do You Reset a Contactor Switch?

Resetting a faulty AC contactor usually involves the following steps:

1. Before doing any work on your air conditioning unit, turn off the electrical power to it.
2. Find the contactor inside your outdoor air conditioning unit (condenser).
3. Manually press the lever or button on the contactor to reset it (in some models of contactors, doing this also repositions the contacts).
4. After resetting the contactor, power to the air conditioning unit can be turned back on and tested to see if this worked for you.

Keep in mind that resetting a contactor is only a temporary solution. If the issue persists after resetting, you should consider replacing the contactor to avoid future complications.

When Should You Replace Your AC Contactor Switch?

When troubleshooting with a defective AC contactor switch (if resetting has failed) or when it has obvious defects (e.g., burnt contacts), it is time for a replacement. A service technician will be able to quickly replace the defective part and check your air conditioning unit for any other underlying issues. If you are confident in doing so and have experience with electrical parts, you may want to try replacing it yourself; however, always follow safe practices and procedures.

Preventive Maintenance for Your Air Conditioning System

To reduce the chances of contactor failure and keep your air conditioning unit operating properly, regular maintenance is extremely important. A few examples include:

1. Clean and inspect components on a regular basis: Accumulation of dirt can lead to overheating and improper operation of electrical parts.
2. Inspect for wear and tear: Performing periodic visual inspections can help detect early deterioration of components.
3. Hire a professional HVAC company: An annual inspection by a certified technician can help prevent expensive damage to the air-conditioning unit.

With the right amount of maintenance and care, your AC contactor switch will last longer and run more reliably throughout the entire year.

Conclusion

Although it may seem like a minor component, failure of the AC contactor switch can lead to major disruptions in your air conditioning system. Understanding how the AC contactor switch operates, recognizing the warning signs, and performing proper maintenance or replacement as needed will save you from downtime and costly repairs. If you are unable to resolve the issue on your own, a qualified licensed HVAC technician can diagnose and replace your failed contactor, allowing your system to operate again at optimal levels in no time.