How to fix a central air conditioner that is smoking

When the familiar hum of a central air conditioning unit is accompanied by the sight of smoke, it’s a clear sign of an underlying issue that requires immediate attention. A smoking air conditioner can be caused by a variety of problems and we’re here to help you tackle this potentially complex issue and restore your home’s cooling system.

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
• Screwdrivers
• Compressed air

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

Inspect the fan motor and bearings:

1. Visually inspect the fan motor for any signs of damage, such as burning, discoloration, or physical wear.
2. Check if the fan motor is spinning freely without any binding or grinding noises.
3. Measure the resistance across the windings of the fan motor using a multimeter. Compare the readings to the manufacturer’s specifications to determine if the motor is faulty.
4. Manually spin the fan blades to see if the bearings are binding or seized.
5. If the bearings are faulty, the fan motor may need to be replaced.

Inspect the electrical switches:

1. Locate the electrical switches, such as the thermostat, fan relay, or safety switches.
2. Use a multimeter to test the switches for proper operation. Check for continuity when the switch is closed and no continuity when the switch is open.
3. Replace any faulty switches that are not functioning properly.

Examine the start relay:

1. Locate the start relay, which is responsible for providing the initial surge of power to start the compressor.
2. Use a multimeter to test the start relay for proper operation. Check the contacts for continuity and ensure the relay is activating when the compressor tries to start.
3. Replace the start relay if it is faulty.

Inspect the wiring:

1. Visually inspect all the wiring connections, looking for signs of moisture, corrosion, or damage.
2. Use a multimeter to test the continuity of the wiring and ensure there are no short circuits or grounding issues.
3. If the wiring is wet, dry it thoroughly and replace any damaged or corroded wires.

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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