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Why does my AC smell? Six Reasons and Solutions

air conditioner smell

Your air conditioning might be the last thing you’d check for if you experience smelling a strange odor. However, it is not uncommon for AC units to emit strange-smelling odors, especially if it’s an old model or has not been tuned up recently. If you’re going through a similar problem and are wondering, “Why does my air conditioner smell?” we’ve got answers.

Listed below are six of the most common smells an air conditioner can produce. We’ve also listed the remedies to counter these smells because we all want our home air to be clean and safe.

Smells Like Chemicals

It's not a good sign if your air conditioner smells unpleasant when switched on, especially if it's chemical-smelling. It may smell like paint thinner or effuse a sweet scent. 

These sweet-smelling chemical odors are a sign that your air conditioner has a refrigerant leak. Your AC uses this gas to move heat through copper coils, which can eventually break and start leaking.

Signs Your AC Has A Refrigerant Leak

Here are four other indications that you have a refrigerant leak, in addition to the peculiar scent.

  • Hissing or bubbling noises when your air conditioner is running.

  • Ice crystals on the evaporator coil or the refrigerant pipes.

  • Maintaining a cold home or maintaining the set temperature is difficult.

  • Excessive energy bills.

How To Fix It

A refrigerant leak is best addressed by a reputable heating and air conditioning company.  Another option can be to take out home warranties that offer best HVAC coverage beforehand to stay protected. In both cases, a skilled technician will locate and fix the leak before adding refrigerant to your AC.

According to national estimates provided by HomeAdvisor, fixing a refrigerant leak typically costs between $225 and $1,600. The location, size, and duration of the repair will all affect how much it will ultimately cost you.

It's likely that your air conditioner uses R-22 or Freon refrigerant if it was installed before 2010. Due to its negative impact on the ozone layer, this refrigerant is no longer produced. It would be best to plan to replace your air conditioner in such an instance as repairs can be very pricey. However, you should be careful while choosing hvac for your child’s room as they are sensitive and can get affected easily.

Smells Like Eggs/Gas

Unless anything is seriously wrong with your air conditioner, it probably doesn't smell like rotten eggs. Natural gas can be fatal in large quantities, however, it has an ingredient that resembles the smell of sulfur. If you smell something akin to that, there is a high probability of a leak and it is best to get it checked out immediately.

How To Fix It

If you smell sulfur or rotting eggs, we suggest that you:

  • Turn off the gas.

  • Open the windows

  • Leave your home right away

  • Contact your gas provider right away.

Smells Musty

People who report this issue usually state that when their air conditioner is running, it smells like feet, dirty socks, or a locker room. This scent, also known as "dirty sock syndrome," is frequently brought on by an unclean evaporator coil and has a buildup of bacteria, mold, and mildew. 

This smell of your home's air conditioner might also be caused by too much water. This phenomenon is most common in areas where heating is used at night and in the morning before changing to cooling in the afternoon.

How To Fix It

The easiest way to avoid dirty sock syndrome is to replace your air filters frequently and arrange regular maintenance for your air conditioner. It is important to keep the evaporator coil clean and the drainage system unclogged because standing water can also produce unpleasant scents.

Smells Like Vinegar

If your air conditioner smells musty or has a strong vinegar-like odor, it could be caused by a number of things, including:

  • A congested filter

  • Excessive condensation

  • Blocked drain line or condensate pan

  • Moldy ductwork or air conditioner

How To Fix It

First, check your filter. If you can't see light through it and haven't changed it in the past three months, it has to be replaced. If the issue isn’t resolved, contact the professionals.

Smells Like Burning Plastic

There may be a few issues if you notice a burning smell coming from your air conditioner or if it smells like fish. These include:

  • The motor is overheating due to a broken capacitor

  • A motor that requires to be lubricated

  • Damaged fan belt

  • Electric problem

How To Fix It

Electrical issues should be checked and dealt with straight away as otherwise, they may cause a fire. When your air conditioner is running, and you smell burning plastic, you should turn it off right away and call the professionals.

Smells Like Ammonia

A strong ammonia smell suggests that mold may be growing in your air conditioner's ducts. Mold doesn't actually smell; rather, the mycotoxins that mold produces do.

How To Fix It

Mycotoxins are extremely dangerous to your health. That’s why it’s important to have HVAC companies examine your air conditioner and ductwork regularly and clean it when necessary.

The Bottom Line

Your HVAC system or air conditioner unit should keep your home cool, warm, or at your ideal temperature and not emit strange or foul odors. It’s best to take care of the system’s maintenance and conduct regular tune-ups to avoid or stay ahead of any potential problems like the above.