Why Is There a Burning Smell Coming From My AC? A Texas Tech Answers


If there’s a strong burning smell every time your AC turns on you’re probably worried and wondering what’s causing the smell.

A burning smell could be produced by several different issues, including:

  • A dirty air filter
  • Worn out bearings
  • A worn fan-belt
  • Electrical issues
  • A bad capacitor

In this blog, we’ll take a closer look at each of these AC issues and how they can cause a burning smell.

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Issue #1: A dirty air filter

Signs this is the source of the smell: Your air filter hasn’t been replaced in a while.

A clogged/dirty filter can block the airflow to important components of your AC system, like the blower motor. With less air coming into the system, your blower motor has to work longer to cool your home. This can put so much stress on your motor that it overheats, producing a burning smell.

Dirty and a Clean Air Filter

A clean air filter (left) vs a dirty air filter (right).

So what’s the fix? Well, if your air filter is noticeably dirty, you should replace it with a clean filter

However, if you’ve tried changing the filter (or the filter was already clean) and the smell persists, your blower motor might need to be replaced or reduced airflow was not the issue. In this case, you’ll need to contact a professional to handle the problem for you.

Issue #2: Worn out bearings

Signs this is the source of the smell: You hear strange high-pitched grinding noises when your AC is running.

Your AC system has two fans: one in the inside unit and one in the outside unit. Both fans are powered by motors. Eventually, the motors’ bearings can wear out, which produces a burning smell.

A technician will usually handle this issue by lubricating the bearings inside the motor. By having the bearings lubricated, you can keep the motor from burning out and spare yourself the costly inconvenience of having to replace the motor altogether.

Keep in mind, though, that there may be permanent damage to the bearings and/or the motors, which might require a more extensive repair.

Issue #3: A worn fan belt

Signs this is the source of the smell:

  • You have an older AC system/unit
  • The odor smells like burning rubber

Homeowners that have an older AC system may have a belt-driven blower fan. If you do, and your AC smells like it’s burning, your fan belt might need to be replaced.

The fan belt (made of rubber) works to spin the fan blades, which passes air throughout your home. Over time, the belt can become weak or wear out completely. Eventually, the fan belt will overheat and create a burning rubber smell.

If you think the fan belt is the source, you should shut off your AC system and contact a technician to replace the belt for you.

Issue #4: Electrical issues

Signs this is the source of the smell: Your AC smells like burning plastic.

Your AC system’s electrical wiring typically has a plastic coating around it. Anything from worn electrical connections to faulty breakers/short circuits can cause the plastic coating on wires to melt, which can result in a burning plastic smell. This can potentially cause damage to other components and even start an electrical fire.

If there is a strong smell of burning plastic in your home, you should shut down your system completely and contact an HVAC technician ASAP. The technician will check your system thoroughly to locate and remedy the faulty/melted electrical equipment.

Issue #5: A bad capacitor

Signs this is the source of the smell: The odor smells like burning plastic BUT the smell is stronger outside your home (near the outside unit).

Every outdoor AC unit has a capacitor. The capacitor is a small cylindrical component that helps to kickstart your outdoor AC’s motor.

a bad ac capacitor

Capacitors tend to go bad because of overheating, power surges or simple deterioration due to old age. In any case, if the capacitor goes bad, it can cause the motor to overheat, which creates that strong burning smell.

If the capacitor is bad, you’re either going to need a capacitor replacement or a motor replacement (if the problem has gone on for some time). In either case, a professional will be able to handle the job.

Looking for a pro technician to repair your AC system? We’re here to help!

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No matter the source, we can rid your home of that foul burning smell and have your system back to normal in no time. All of our technicians follow the highest industry standards and offer world-class customer service for every repair. No games. No Gimmicks. Just Reliable!

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