Why Does My Air Conditioner Smell Like Chemicals?

June 08, 2017

If you’ve noticed a chemical-like smell when the air conditioner is running, you most likely have one of the following problems:

  • Refrigerant leak
  • Dirty or moldy evaporator coil/ductworks
  • Open chemicals near return vents
  • Electronic air cleaner producing ozone

 To help you troubleshoot and determine what’s causing the smell, let’s look at each of these smelly situations a bit closer.

 Need a professional to check out the smell ASAP? Just contact us and we'll send one over.

Problem #1: A refrigerant leak

Signs that this is your problem:

  • Higher-than-usual cooling bills
  • AC struggles to cool your home
  • Ice on refrigerant lines (or frozen evaporator coil)
  • A hissing or bubbling noise along your refrigerant lines

Your AC uses refrigerant to absorb the warmth and moisture from the air in your home. And, in normal operation, that refrigerant is contained inside refrigerant coils that run throughout the entire AC system.

But over time, wear and tear can cause small cracks and holes along those coils, allowing refrigerant to waft out and into your home.

Most refrigerants themselves do not create a strong chemical smell. So, if you have a refrigerant leak, you likely won’t be smelling the refrigerant itself but the oil mixed into the refrigerant as a lubricant.

What to do:

Have a professional inspect your system for a refrigerant leak. Once they find the leak, they should first repair the leak then recharge your system with more refrigerant.

Problem #2: Mold in your evaporator coil/ductwork

Signs that this is your problem:

  • Chemical smell is slightly musty or acidic
  • Visible mold growth on evaporator coil
  • You may be able to see mold when you peer into ductwork

Mold loves dark, damp areas that also provide dirt and bacteria to feed off of. And unfortunately, your AC system offers all those things. And if mold starts growing in your AC system, you’ll soon start to smell mycotoxins, the metabolic byproduct of mold, especially during cooling cycles.

Many people have reported mycotoxins smelling earthy, musty or even like “dirty socks” but some mycotoxins can also smell like ammonia and other chemicals.

What to do:

Have a professional inspect your AC system and ductwork for mold. Some solutions for this problem include:

  • Downsizing your AC unit (if it’s oversized)
  • Setting your thermostat fan setting to AUTO instead of ON
  • Installing ductwork insulation

Note: If your AC is producing a chemical smell and you just had your evaporator coil cleaned, it could be the coil cleaner that you’re smelling. Call a professional if the chemical smell persists 2 weeks or more from when the coils were cleaned.

Problem #3: Chemicals pulled into AC system from your home

Signs this is your problem:

  • Open or pungent chemical containers sitting near your return vents

Your return vents are responsible for pulling air into the AC system to be cooled then dispersed throughout your home. So, if you have open containers of chemicals sitting near these vents, the chemical smell will be dispersed throughout the ductwork and pushed into your entire home.

What to do:

Check all return vents in your home. Make sure there are no chemicals near these vents.

Return vent in a home

Be sure to check for containers of:

  • Cans of paint

  • Cleaning supplies

  • Automotive chemicals

If you see any unsealed chemicals, seal them off or move them away from the return vents.

Problem #4: Electronic air cleaner producing ozone

Signs this is your problem:

  • You’re currently using an electronic air cleaner in your HVAC system
  • The smell coming from your AC vents smells like chlorine

Many electronic air cleaners produce “ozone”, a natural gas with a pungent, chlorine smell. But while you can smell the ozone produced by your electronic air cleaner, you don’t need to worry about it being harmful to your health.

Most electronic air cleaners produce around .005 to .020 parts per million (PPM) of ozone, which is well below the acceptable indoor ozone levels set by the Food and Drug Administration (.050 PPM).

What to do:

  1. Clean the electronic air cleaner. The dirtier the cells are in your air cleaner, the less effectively they work.

  2. Make sure your fan is set to AUTO not ON. Most electronic air cleaners are wired to operate only when the fan is running. But if you set your fan to ON, the fan runs nonstop (meaning the air cleaner will also run non-stop). And the longer your electronic air cleaner runs, the more ozone it produces. So keep your fan set to AUTO to ensure your fan and electronic air cleaner only run when the AC is cooling.

  3. Ask a technician to inspect your electronic air cleaner if the smell still bothers you. They’ll be able to check for larger problems such as a loose or broken ionizing wire or an air cleaner that’s too big for your home.

Do you still smell chemicals from your AC? Ask a Kansas City tech

Just contact us and we’ll send over a professional to diagnose and fix the problem that’s causing your air conditioner to smell.

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