Troubleshooting a central air conditioner that has a bad odor

Nothing is more unpleasant than turning on your central AC only to be greeted by a musty or foul odor. These persistent bad smells signal bigger problems that require prompt attention. We’re here to hlpe with common odor causes, troubleshooting steps, and solutions to eliminate those unpleasant smells and restore a fresh, comfortable environment.

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

• Cleaning supplies
• New air filter

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

Dirty air filters:

1. Clogged or dirty air filters restrict airflow, causing dirt, dust, and other particulates to accumulate in the system.
2. As this debris builds up, it can produce a musty, stale odor that gets blown into the living spaces.
3. Regularly replacing the air filters is an easy way to maintain clean, fresh-smelling air circulation.

Mold and mildew growth:

1. The warm, humid environment inside the air handler unit and ductwork provides an ideal breeding ground for mold and mildew.
2. Condensation can accumulate on the evaporator coil, in the drain pan, and in other areas, leading to microbial growth.
3. Over time, the musty, earthy smell of mold can be circulated throughout the home.
4. Regular cleaning and maintenance of the coils, drain pans, and ductwork is important to prevent mold buildup.

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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