what wire are on ac contactor



When it comes to understanding the wirings on an AC contactor, it is essential to have a clear understanding of the different components and connections. The AC contactor is a crucial part of the air conditioning unit that allows for the engagement and disengagement of the power supply to the compressor and condenser fan motor. It is important to know which wires are connected to the AC contactor as they play a significant role in the overall functionality of the unit. In this article, we will explore the different wires used on an AC contactor and how they contribute to its operation.

The Main Power Supply Wires (L1 and L2)

The main power supply wires, commonly referred to as L1 and L2, are the primary wires that carry the electrical current to the AC contactor. These wires are typically connected from the main electrical panel to the contactor. The L1 wire carries the current from one phase of the power supply, while the L2 wire carries the current from the other phase. It is crucial to ensure that these wires are properly connected to their respective terminals on the contactor to provide a stable power supply.

The main power supply wires are usually connected to the top terminals of the contactor, often labeled as T1 and T2. These terminals are typically positioned away from the other terminals to avoid any confusion while making the connections. It is important to note that before working on the AC contactor, you should always turn off the power supply by switching off the circuit breaker or disconnecting the power source to ensure safety.

When connecting the main power supply wires to the contactor, it is recommended to use suitable cables and connectors capable of handling the required voltage and current. Proper insulation and secure connections are essential for the safe and efficient operation of the air conditioning unit. Improperly connected main power supply wires can result in electrical faults, which may potentially damage the unit or pose a risk to the users.

The Control Wires (Low Voltage Wires)

Apart from the main power supply wires, an AC contactor also requires control wires to enable the unit to operate according to the desired settings. These control wires, also known as low voltage wires, are responsible for transmitting signals from various control devices, such as thermostats and pressure switches, to the contactor. The control wires play a crucial role in regulating the operation of the air conditioning unit and ensuring the appropriate cooling or heating effect.

The control wires are typically connected to a separate section of the contactor, often labeled as "A1" and "A2." These terminals are specifically designed for low voltage connections and are distinctively placed away from the high voltage terminals. As these wires carry lower voltage levels, they pose a significantly lower risk of electric shock, but it is still important to ensure proper precautions and safety measures are followed while working on them.

When connecting the control wires, it is essential to refer to the wiring diagram provided by the manufacturer. The wiring diagrams depict the correct connections, color codes, and wire sizes specific to the particular model of the air conditioning unit. Following the manufacturer's guidelines ensures the proper functioning of the control system and avoids any unnecessary complications.

The Contactor Coil Wires

The contactor coil wires are an integral part of the AC contactor that is responsible for controlling the engagement and disengagement of the contacts. The contactor coil is essentially an electromagnet that, when energized, attracts the contacts, allowing the electrical current to flow through them. The coil wires are connected to the control circuit and are controlled by the control device, such as the thermostat or the control board.

The contactor coil wires are typically labeled as "C1" and "C2" and are connected to the coil terminals of the contactor. These terminals are situated near the control terminal section, ensuring ease of connection and minimizing any confusion with the high voltage terminals. The coil wires are smaller in size compared to the main power supply wires as they carry significantly lower current values.

It is important to understand the voltage requirements of the contactor coil and ensure that the control voltage matches the voltage rating of the coil. Using a coil with an incompatible voltage rating can result in improper operation of the unit or even damage to the contactor. Similarly, it is essential to connect the control wires to the right terminals and maintain proper insulation and secure connections to prevent any electrical faults.

The Auxiliary Contacts

Auxiliary contacts are additional components present in some AC contactors that provide auxiliary functions like signaling, interlocking, or controlling other devices. These contacts are typically used in situations where the main power contacts alone cannot fulfill all the requirements of the control circuit. The auxiliary contacts are activated in conjunction with the main power contacts and can be connected to various control devices or accessories.

Auxiliary contacts can be of different types, such as normally open (NO) or normally closed (NC), and can have multiple sets depending on the contactor model. These contacts are interconnected with the main contacts and are often labeled as "AUX" or "T." The connection of the auxiliary contacts can vary depending on the specific requirements of the control circuit, and the manufacturer's instructions should always be followed during installation.


Understanding the different wires on an AC contactor is crucial for the safe and efficient operation of an air conditioning unit. By familiarizing yourself with the main power supply wires, control wires, contactor coil wires, and auxiliary contacts, you can ensure proper installation, connection, and functionality of the AC contactor. Always refer to the manufacturer's guidelines and wiring diagrams for accurate connections, wire sizes, and color codes specific to your unit. Taking the necessary precautions and following the appropriate procedures will help you maintain a reliable and secure electrical system in your air conditioning unit.


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