Decoded: Eight Different Air Conditioner Smells

Have you turned on your air conditioner only to find a bizarre smell suddenly filling the air? Every now and then, a bad odor is actually a sign that your air conditioner is experiencing a problem. Maintenance or even a repair might be necessary if you want the smell to go away. But what kind of smell can actually help you determine what the problem is. Continue below for eight common smells that may come from your AC system and what each means.

1. Air conditioner smells musty

A smell that resembles mold or dirty gym socks is often traced back to the evaporator coil, where mold, mildew and bacteria may have appeared. If your AC smells like dirty socks or stinky feet, this is often a moisture issue likely caused by a dirty or clogged up unit. There may be sitting water that’s unable to drain properly. To eliminate the smell, a thorough cleaning from a local professional usually resolves the issue.

2. Air conditioner smells like vinegar

Over time, microorganisms and other organic material like skin flakes will accumulate on the air filter or other parts of the ventilation. When your air conditioner smells like vinegar, it’s most likely due to a clog of this organic matter blocking the condensate pan or drain line. Eliminating the smell may be as simple as replacing the air filter, but the experts at Simons Heating & Cooling can help find a solution if the filter isn’t clogged.

3. Air conditioner smells like burning rubber

Like many mechanical systems, air conditioners are at risk of overheating. Damage to internal components or a clogged air filter can increase the amount of heat stuck inside the air conditioner, contributing to overheating and often producing a smell like burning rubber. Safety switches should keep the AC from running as long as it’s overheating, so a burning smell should clue you in to call Simons right away! We’ll restore normal operation as soon as we can.

4. Air conditioner smells like fish

A fishy, metallic smell often stems from an electrical component damaged by overheating. Frayed wiring, overloaded circuits and damage to the insulation can all overheat the electrical connections. Look for dust or mold blocking airflow if you suspect your air conditioner is overheating.

5. Air conditioner smells like urine

If your air conditioner is producing a foul chemical scent similar to ammonia or even urine, it may be due to a blocked drain line. When the condensate in the bottom pan cannot fully drain out, it may collect dust, dirt and bacteria capable of producing this telltale, musty odor. Another possible cause is low refrigerant levels. Older units use Freon, which was permanently discontinued in the U.S. in 2020 due to environmental concerns. Since 2010, most residential AC units use a refrigerant called R410A or Puron. Your Simons technician will check the coolant levels if they smell ammonia.

6. Air conditioner smells like gas or rotten eggs

Typically, a gas or rotten egg smell is because the air conditioning possesses a gas-powered compressor. Special chemicals are added to the gas for easy detection in case there’s a leak. As such, you shouldn’t notice this smell during normal AC operation. Whenever you smell gas in your home, leave the property immediately before contacting emergency services and your utility company. Once the risk is cleared, a professional can start looking for the gas leak in the AC system or somewhere nearby so repairs can begin.

7. Air conditioner smells sweet or floral

It is likely that the sweet smell you are noticing is a Freon (for older units) or Puron (for newer AC units) leak. These products have a sweet chloroform smell and when it leaks, it can fill the air with this sweet scent. You should have a professional inspect your air conditioner to determine if this is the cause. If it is a Freon or Puron leak, it should be fixed as soon as possible to avoid any further damage to the AC unit or ground contamination. Additionally, you should also check the cooling coil and drain pan for mold or mildew, as this can lead to a musty, unpleasant smell coming into your Upstate New York home.

You may not think that a sweet, floral smell could ever be a bad thing, but it’s possible that the pleasant odor is actually the result of a refrigerant leak. Freon and Puron have scents that resemble a sweet chloroform aroma. If it’s indeed a coolant leak, you should try to get it repaired promptly to avoid further damage.

8. Air conditioner smells like cigarette smoke

If you or someone in your household smokes regularly, the smoke particles can settle against the AC’s evaporator coil and gradually accumulate. We recommend having the coils cleaned by an HVAC professional before replacing the air filter. This minor maintenance task may need to be performed more regularly in homes with smoking.

No matter what the root cause is, feel free to call Simons Heating & Cooling when you suspect a problem with your air conditioner. If you smell trouble, let us know right away! Schedule repair or maintenance service by giving us a call at (518) 839-2602 today.