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Why Does My A/C Smell?

HVAC technician repairing an outdoor AC unit

When you turn on your AC, have you ever smelled something unusual? Maybe like a wet sock or a weird chemical smell? It can be overwhelming and lead you to just turning off your system so you don’t have to worry about the smell anymore.

We’ll go over the different types of AC smells, what they mean, and when to call your local A/C repair company.

What Different AC Smells Mean

Your HVAC system shouldn’t smell like anything, but there are a lot of different scents that can come from an air conditioner, with each one meaning a different thing. From mustiness to a chemical-like odor, each scent typically indicates one of the following common AC problems:

If the A/C Smells Musty…

It is very common for an air conditioner to smell musty. This scent means there is a buildup of mold or bacteria somewhere within the system. Check your AC system for the following situations to find the source of the mustiness:

  • A full drain pan
  • Excess moisture in ducts
  • Dirty air filter

Of these three, a dirty air filter is the easiest to spot and fix – just check the air filters and replace them if necessary. If you do change the filter and that doesn’t get rid of the musty smell, call an HVAC company for further assistance.

If the A/C Smells like Gas or Rotten Eggs…

If your A/C smells like gas or rotten eggs, the worst-case scenario is that it could be a gas leak. If you suspect this is the case, turn off your system and call an HVAC company immediately. They’ll be able to safely inspect your air conditioner, determine if this is the problem, and fix it right away.

A rotten egg smell can also mean there is a dead rodent stuck somewhere in your system. An HVAC company will let you know if this is the case and recommend that you call pest control to handle it.

If the A/C Smells like Burning Rubber…

If you smell burning rubber or a metallic scent, this can mean:

  • The A/C’s motor could be overheating
  • Electrical components could be burning
  • Dust is burning off

If you are smelling this scent, completely turn off your AC system and gas. Then open all your windows and call an HVAC company for repair.

If the A/C Smells like Chemicals…

There are a few different distinct chemical smells and ways to handle them.

Sweet Smells

If you smell ether, chloroform, or sweetness, your system is likely leaking refrigerant and you should call an HVAC company to handle it.

Sour Smells

If your AC system smells sour, you probably have an ozone leak. This can be caused by electrostatic air filters. You should lower the settings on the air filter and see if that makes a difference. If not, call an HVAC company so an air quality expert can take a look at the system.

Foul Smells

If there’s a foul smell coming from your system, you could have a dirty evaporator coil. You can handle this yourself by turning off the system, taking out the evaporator coils, and cleaning them yourself. However, disassembling parts of your A/C can take some technical know-how. If you aren’t comfortable doing this yourself, schedule routine A/C maintenance and one of our HVAC technicians cant take care of it.

Cleaning Products or Paint Smells

Lastly, if you are smelling a chemical scent similar to cleaning products or paint, you should check to see how close your cleaning products or paint cans are to your system. They are likely too close to the AC and need to be moved away to get rid of the smell.

How to Prevent Strange AC Smells

The best way to prevent your air conditioning system from smelling like anything above is by scheduling routine maintenance. An HVAC technician will be able to catch any issues before they turn into a smelly problem.

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