where is the contactor on an ac unit



When it comes to air conditioning units, there are various components that work together to ensure optimal cooling performance. One crucial component in an AC unit is the contactor. The contactor plays a vital role in the overall functioning of the system, controlling the flow of electrical currents. However, locating the contactor in an AC unit may not be as straightforward for many people. In this article, we will delve into the question of "where is the contactor on an AC unit?" and provide you with a comprehensive understanding of its placement, function, and importance.

The Importance of the Contactor:

The contactor in an AC unit serves as a switch that activates and deactivates the compressor, condenser fan motor, and blower motor. It is responsible for controlling the electrical flow, ensuring that the appropriate components receive power when necessary. The contactor essentially acts as a bridge between the thermostat and the various electrical components of the air conditioning system.

The Placement of the Contactor:

Understanding the Placement of the Contactor

To locate the contactor in an AC unit, you first need to have a basic understanding of the unit's anatomy. Most AC units have an outer casing that encloses the internal components. The contactor is typically located within this casing, often near the compressor and condenser fan motor. However, the specific position may vary depending on the AC model and manufacturer.

How to Locate the Contactor:

Locating the Contactor in Central Air Conditioning Units

To locate the contactor in a central air conditioning unit, you should follow the steps below:

1. Turn Off the Power: Prior to inspecting any part of the AC unit, it is crucial to turn off the power supply. This will prevent any accidental electrical shocks and ensure your safety.

2. Access the Air Handler: In most cases, the air handler is located indoors, often in a basement, attic, or utility closet. Locate the access panel and remove the screws or fasteners to open it.

3. Identify the Electrical Panel: Once you have accessed the air handler, locate the electrical panel. This panel contains various electrical components, including the contactor. It is usually a large metal box with removable panels.

4. Inspect the Electrical Panel: Within the electrical panel, you will find several components mounted on a metal plate. The contactor is typically one of the larger components, often covered by a plastic or metal housing.

5. Identify the Contactor: The contactor can be recognized by its distinctive appearance. It consists of multiple terminals and a set of contacts that close when the current flows through. The contacts are usually made of silver or copper, known for their excellent electrical conductivity.

6. Verify the Contactor Label: To ensure you have found the contactor, check for a label or marking. The label may indicate "contactor" or have other related information. This verification will provide certainty about the component you have located.

7. Proceed with Caution: Remember, even when the power is turned off, certain components may still store electrical charges. To avoid any accidents, it is essential to be cautious and avoid touching any electrical parts unless you are qualified to do so.

Locating the Contactor in Window Units

Finding the contactor in a window unit may be somewhat different compared to central air conditioning units. Here are the steps to locate the contactor in a window unit:

1. Turn Off the Power: Begin by disconnecting the power supply to the window unit. Unplug it or switch off the relevant circuit breaker to ensure your safety.

2. Remove Outer Cover: Unscrew or unclip the outer cover of the window unit. This will provide access to the internal componentry.

3. Locate the Electrical Components: Within the unit, you will find several electrical components. The contactor might be located near the compressor or within the control panel. Refer to the unit's user manual for specific details.

4. Visual Identification of the Contactor: Identify the contactor by searching for a relay-type switch. It might be encased in a plastic housing or metal cover, designed to protect the electrical connections.

5. Confirm the Contactor: Once you have identified the component that you believe is the contactor, examine it for any labeling or marking. This will help to confirm its identity.

Understanding the Contactor's Components:

The contactor consists of various components that work together to control the electrical flow. Understanding these parts will help you gain a comprehensive understanding of the contactor's functioning.

1. Coil: The coil is an essential part of the contactor that creates the electromagnetic field required to open and close the contacts. When energized, the coil produces a magnetic force that attracts the contacts, allowing the electrical flow to occur.

2. Contacts: The contacts within the contactor are the actual switches that open and close when powered. These contacts are responsible for controlling the flow of electrical current to different AC components.

3. Terminals: The contactor has multiple terminals, which are metal connectors for the electrical wires. These terminals receive the electrical connections and ensure proper contact with the contacts and coil.

4. Housing: Contactors often have a housing, either plastic or metal, to encase the internal components. This housing protects the contacts and coil, providing insulation and safeguarding against physical damage and environmental factors.


In conclusion, the contactor plays a crucial role in the operation of an AC unit, controlling the electrical flow to various components. While locating the contactor may seem challenging, understanding the unit's anatomy, and following specific steps can simplify the process. Whether you are inspecting a central air conditioning unit or a window unit, turning off the power and exercising caution is imperative. By familiarizing yourself with the contactor's components and their functions, you will have a better grasp of how this integral part works in harmony with the other elements of your AC system. Remember, if you are unsure or uncomfortable handling any electrical components, it is always best to seek professional assistance to ensure safety and optimal functionality of your AC unit.


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