how to change ac contactor



Changing the AC contactor is a task that can be performed by homeowners with basic knowledge and understanding of electrical systems. The AC contactor is an essential component of the air conditioning system, responsible for controlling the flow of electricity to the compressor and fan motor. Over time, contactors can become worn out or damaged, leading to issues with the functioning of the AC unit. In this article, we will discuss the step-by-step process of changing the AC contactor, ensuring a smooth and efficient operation of your air conditioning system.

Why Should You Change the AC Contactor?

The AC contactor plays a crucial role in the overall functionality of the air conditioning system. Over time, wear and tear, electrical surges, or other factors can lead to malfunctioning or damaged contactors. Here are a few reasons why you might need to change the AC contactor:

Electrical Issues: Faulty contactors can result in electrical issues, such as shorts or tripped circuit breakers. Changing the contactor can help resolve these problems and prevent potential hazards.

Poor Cooling: If your air conditioning system is not providing adequate cooling or taking longer to reach the desired temperature, a faulty contactor could be the culprit. Changing the contactor can help restore the cooling capacity of your AC unit.

Loud or Unusual Noises: A worn-out contactor can produce buzzing or humming sounds when the system is running. Replacing the contactor can eliminate these noises and restore peace and quiet to your indoor environment.

Increased Energy Consumption: A faulty contactor may cause the AC system to draw excessive power, leading to increased energy consumption and higher utility bills. Changing the contactor can help improve energy efficiency.

Poor Airflow: Malfunctioning contactors can result in reduced airflow from the vents, compromising the overall comfort of your living space. Replacing the contactor can ensure proper airflow and enhance the efficiency of your air conditioning system.

The Step-by-Step Guide to Changing the AC Contactor

Follow these simple steps to safely change the AC contactor in your air conditioning system:

Safety Precautions: Prior to starting any work, it is essential to ensure your safety. Turn off the power to the air conditioning system by switching off the circuit breaker associated with the unit. Use a voltage tester to verify that the power is indeed turned off.

Locate the Contactor: The contactor is typically located inside the outdoor unit of the air conditioner. Open the access panel to expose the contactor. Make sure to familiarize yourself with the wires connected to the contactor, as you will be disconnecting and reconnecting them during the replacement process.

Label the Wires: To avoid confusion later on, use colored electrical tape or labels to mark each wire connected to the contactor. This step will ensure that you reconnect the wires correctly after replacing the contactor.

Disconnect the Wires: Using a screwdriver or pliers, carefully loosen and remove the screws or connectors holding the wires in place. As you disconnect each wire, attach it to the corresponding labeled wire to prevent any mix-ups.

Remove the Old Contactor: After disconnecting all the wires, remove the old contactor from its housing. Take note of how the contactor is positioned and mounted so that you can install the new one correctly.

Install the New Contactor: Position the new contactor in the same way the old one was installed. Ensure that it is securely mounted in place and aligns with the screw holes. Insert and tighten the screws to hold the contactor firmly.

Reconnect the Wires: Refer to the labels or colored tape you placed on the wires earlier. Connect each wire to the respective terminal on the new contactor. Ensure a tight connection but be careful not to overtighten or damage the terminals.

Test the System: Now that the new contactor is installed and all the wires are connected, it's time to test the system. Turn on the power by switching the circuit breaker back on. Set the thermostat to your desired temperature and check if the AC unit starts up and runs smoothly.


Replacing the AC contactor is a task that can be accomplished by homeowners with basic electrical knowledge. By following the step-by-step guide mentioned above, you can change the contactor in your air conditioning system and restore its proper functioning. Remember to prioritize safety by turning off the power and taking necessary precautions throughout the process. If you encounter any difficulties or are unsure about any steps, it is advisable to seek professional assistance. By taking care of your AC contactor, you can ensure optimal cooling performance and extend the lifespan of your air conditioning system.


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