Troubleshooting a central air conditioner that turns on and off

If your central air conditioner compressor is turning on and off repeatedly, not only is this erratic behavior a nuisance, but it can also lead to skyrocketing energy bills and long-term damage to your unit’s sensitive parts. With some troubleshooting information, you can get to the root of the issue and restore reliable, efficient cooling to your home. 

If you find out that you need any replacement parts for your appliance while you’re troubleshooting, you can enter your model number at AppliancePartsPros.com to order them. Most orders arrive in just two business days, and we have thousands of free guides to show you how to install your new parts.

The troubleshooting information provided in this article may not apply to your specific appliance model. While we strive to offer helpful advice for DIY appliance repairs, variations in models and configurations can lead to differences in troubleshooting steps, error codes and part replacements. For the most accurate guidance, we strongly recommend consulting the technical sheet for your specific appliance model.

Safety precautions

When working on any appliance, remember to keep safety first. Here are some tips to keep in mind: 

• Always power off and unplug your appliance or switch off the circuit breaker before attempting any maintenance or replacement work. This keeps you safe by preventing any risk of injury from electric shock.
• Wear insulated work gloves to protect your hands from sharp metal parts, pinching hazards and debris.
• Take your time and don’t rush while working to prevent accidents and personal injuries.
• Work in a well-lit area so you can clearly see and access the interior parts.
• Clear your workspace of clutter and other obstacles. Keep children and pets away from the work area.
• Never work on internal parts with bare wet hands. Make sure the work area is completely dry.
• Check your user manual to see if there are specific installation or safety instructions for your part or appliance. 
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause injury.
• Wear safety glasses when working with chemicals, dust or cleaning large debris to prevent injury. 
• If the appliance has recently been used, give it plenty of time for any heating parts to cool down before working on it. 
• Take pictures or make a note of wiring terminals or other connections before disconnecting to prevent any problems with reassembly.
• When working with wires, avoid touching any exposed wires or terminals. If you need to touch a wire, use a non-conductive tool or wear insulating gloves to prevent electrical shock.

Tools and materials needed

• Multimeter
• Coil cleaner
• Soft brush
• Screwdrivers

The specific tools required may vary depending on the model of your appliance and the type of fasteners used on it. Always consult the user manual or refer to any specific instructions provided by the manufacturer for the recommended tools for your appliance model.

Troubleshooting steps

Thermostat or control incorrectly set

1. Check that the thermostat or control is set to “cool” mode and the temperature setting is lower than the current room temperature.
2. Ensure the thermostat is not set to an auto or fan-only mode.
3. If the thermostat settings are incorrect, adjust the temperature setting and mode as needed.

Overload switch faulty

1. Disconnect the power to the unit, either at the circuit breaker or by unplugging the power cord.
2. Remove the access panel on the condenser unit.
3. Identify the overload switch, which is a safety device that cuts power to the compressor if it overheats.
4. Test the overload switch with a multimeter to check if it is opening and closing properly.
5. If the overload switch is faulty, replace it with a compatible replacement.

Condenser air flow blocked

1. Inspect the outdoor condenser unit for any obstructions, such as debris, vegetation, or objects blocking the airflow.
2. Clear away any obstructions, ensuring a minimum of 2 feet of clearance around the unit.
3. Clean the condenser coils using a coil cleaner and a soft brush, being careful not to bend the delicate fins.
4. Check that the condenser fan is running properly and drawing air through the coils.

Thermostat sensor bulb out of position

1. Identify the sensor bulb, which is typically a small glass bulb connected to the thermostat by a capillary tube.
2. Ensure the sensor bulb is securely mounted in the correct position, usually behind the thermostat cover or in the airflow path.
3. If the sensor bulb is out of position, gently reposition it and secure it in place.

Additional information

Thank you for reading! We hope this guide helped you get your central air conditioner working again.

If you have any other appliance repair needs or projects, don’t hesitate to explore our other troubleshooting guides and videos. 

If you need replacement parts or some extra help with ordering them, grab your model number and head over to AppliancePartsPros.com, where you can chat with a pro, read our DIY blog and more.

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Keep Reading:

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Choosing An Air Conditioner: How Many BTUs Do I Need?  

Diy Mrcool Units: Do Your Own Heating And Air Conditioning