how to bypass outside ac unit contactor switch


How to Bypass Outside AC Unit Contactor Switch


Having an air conditioning unit is a necessity for many households, especially during hot summer months. However, there may be instances when you need to bypass the outside AC unit's contactor switch. Whether you need to perform maintenance or troubleshooting tasks, understanding how to safely bypass this switch is essential. In this article, we will provide step-by-step instructions to help you bypass the outside AC unit's contactor switch effectively. Remember to exercise caution and follow all safety guidelines when working with electrical equipment.

Understanding the AC Unit Contactor Switch

AC unit contactor switches play a crucial role in controlling the flow of electricity to the outdoor AC unit. When the thermostat signals the need for cooling, the contactor switch activates, allowing electrical current to flow through the unit. The switch consists of a coil and contacts that connect and disconnect the power supply to the compressor and condenser fan. However, there may be occasions when you need to bypass this switch to safely perform maintenance or troubleshooting tasks.

Bypassing the outside AC unit contactor switch involves directly supplying power to the compressor and condenser fan, effectively circumventing the switch's function. This allows you to test various components, check for faulty parts, or clean the unit without interference from the switch.

Important Safety Precautions

It is crucial to prioritize your safety when working with electrical equipment. Before attempting to bypass the outside AC unit contactor switch, take the following safety precautions:

1. Always turn off the AC unit: Before starting any work, turn off the AC unit's power supply at the circuit breaker or disconnect switch. This will prevent accidental electrical shocks.

2. Wear protective gear: When working with electrical equipment, wear appropriate protective gear, including safety glasses, gloves, and non-conductive shoes. It is essential to protect yourself from potential hazards.

3. Avoid moisture and wet surfaces: Ensure that the working area is dry and free from any standing water. Moisture can increase the risk of electrical shock, so it’s important to keep electrical components dry.

4. Understand the electrical system: Familiarize yourself with the electrical system before attempting any bypassing procedures. If you feel uncomfortable or uncertain, it is always best to consult a professional technician.

Now let's delve into the step-by-step process of bypassing the outside AC unit contactor switch:

Gather the Necessary Tools

To successfully bypass the outside AC unit contactor switch, you will need the following tools:

1. Screwdriver set: A set of screwdrivers will be required to remove the access panel on the outdoor unit. Make sure you have a screwdriver that fits the specific screws on your unit.

2. Wire strippers: Wire strippers are needed to remove the insulation from the wires and make proper connections. Ensure you have a pair that matches the size of the wires you will be working with.

3. Electrical tape: Electrical tape is essential for insulating wire connections and preventing electrical shorts.

4. Multimeter: A multimeter is a valuable tool for measuring voltage, resistance, and continuity. It will help you troubleshoot and test components throughout the bypassing process.

5. Wire connectors: Wire connectors are used to make secure and reliable connections between wires.

Step 1: Power Off the AC Unit

As mentioned earlier, always turn off the power supply to the AC unit before starting any work. Locate the circuit breaker or disconnect switch that controls the AC unit and turn it off. This step is crucial for your safety.

Step 2: Remove the Access Panel

Once the power is turned off, use the appropriate screwdriver to remove the access panel on the outdoor unit. Carefully set the panel aside in a safe location, ensuring you do not misplace any screws.

Step 3: Identify the Contactor Switch

Locate the contactor switch inside the outdoor unit. It is typically a small box-shaped component with wires connected to it. You can consult the unit's manual or do a quick online search to identify the specific location if needed.

Step 4: Disconnect the Wires

Using the appropriate screwdriver or wrench, carefully remove the wires connected to the contactor switch. Take note of the wire positions and colors for reconnection later. Use caution when handling the wires to avoid damage.

Step 5: Insulate the Disconnected Wires

To ensure safety and prevent any accidental electrical contact, it is important to insulate the disconnected wires properly. Each wire should be insulated individually using electrical tape. Wrap the tape around the exposed copper part, covering it completely.

Bypassing the Contactor Switch

After you have followed the initial steps, you are ready to bypass the contactor switch and provide power directly to the compressor and condenser fan. The following steps will guide you through the bypassing process:

Step 6: Identify the Power Supply Wires

Within the outdoor unit, locate the power supply wires that deliver electricity to the contactor switch. These wires are often connected to the main wiring panel in the unit. They will provide the power necessary to bypass the contactor switch.

Step 7: Strip the Power Supply Wires

Using wire strippers, carefully remove a small section of insulation from the power supply wires. Make sure to strip an equal length on each wire to ensure a proper connection.

Step 8: Connect the Bypass Wires

Take the wires connected directly to the compressor and condenser fan and strip a small section of insulation from the ends. Connect these ends to the stripped sections of the power supply wires, making sure they are tightly secured. Use wire connectors to ensure a reliable and secure connection.

Step 9: Secure the Bypass Wiring

To prevent any loose or exposed wiring, carefully secure the bypass wiring using cable ties or electrical tape. Ensure that all connections are tight and properly insulated to avoid electrical hazards or shorts.

Step 10: Test the Bypassed AC Unit

Once the bypassing process is complete and all connections are secure, you can proceed to test the bypassed AC unit. Turn on the power supply to the unit at the circuit breaker or disconnect switch. Monitor the operation of the compressor and condenser fan to ensure they are running smoothly and without any issues.


Bypassing the outside AC unit contactor switch can facilitate maintenance and troubleshooting tasks. This article provided an in-depth guide to help you understand the process and complete it safely. Remember to prioritize your safety throughout the process, and consult a professional if you feel uncertain or uncomfortable. By bypassing the contactor switch effectively and exercising caution, you can ensure the efficient functioning of your AC unit for years to come.


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