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Air Conditioner Smells Like Gas

Air Conditioner Smells Like Gas: What To Do About This & Other Smells

If your air conditioner smells like gas, mildew, urine, or other unpleasantries, you’d be wise to take a closer look. In this post, we’ll explore some of the common explanations for odd smells as well as what you ought to do.

We’ll tackle this topic by taking a look at each smell individually.

Air Conditioner Smells Like Gas/Rotten Eggs

If your air conditioner smells like rotten eggs (which is perhaps the best way to describe a “gassy” smell), you are almost certainly dealing with a natural gas leak.

While natural gas itself is odorless, many utility companies add chemicals that smell like rotten eggs to the mix in order to help people easily identify a leak. This has been standard practice since 294 people died at a school in Texas during the 1930s as the result of a gas leak.

Despite this safety feature, natural gas explosions still happen regularly in the United States. Anything that produces a spark (such as your water heater’s pilot light) can cause the deadly ignition of natural gas in your home.

What To Do About It

Due to the severity of a gas leak, it’s absolutely imperative that you do the following if your air conditioner smells like rotten eggs.

  1. Immediately open your home’s windows to dispel some of the gas
  2. Promptly evacuate your home
  3. Contact your gas company immediately and follow their instructions (which may include shutting off your home’s gas supply if this is possible)

If the smell is very strong and has been present for some time, consider skipping the first step and simply evacuate your home. Prolonged exposure to high levels of natural gas can cause loss of consciousness and even death.

Air Conditioner Smells Like Mildew

If your air conditioner smells like mildew, you’re experiencing what people often refer to as “dirty sock syndrome.” While this doesn’t represent something as drastic as an imminent explosion, it’s still quite bad for your health.

The smell is caused by a buildup of bacteria, moisture, and mold in your air conditioner. If your air conditioner is leaking water and you haven’t cleaned it out in a while, you’re very likely to encounter this problem.

What To Do About It

Of course, you don’t want to be breathing in air that’s been contaminated with bacteria such as mold. In severe instances, this can lead to coughing, wheezing, rashes, and other unpleasant symptoms.

Here are the steps you should take to remedy this issue.

  1. Turn your AC off at the circuit breaker and thermostat.
  2. Check your drain line for blockage and clear it if necessary.
  3. Replace your air conditioner filter if it has gotten overly wet.
  4. Vacuum your evaporator coil with a shop vac and then scrub it thoroughly using a bleach/water mixture.
  5. Dry the evaporator coils with paper towels before running your shop vac over the area once more to get rid of any leftover moisture.
  6. Reassemble the air conditioner and wash your hands. Make sure to dispose of any towels or sponges you used to clean the evaporator coil.

As you can see, this process is somewhat involved and requires at least some understanding of your air conditioner’s construction. If you require assistance and live in the Phoenix, Arizona area, contact us at American Home Water and Air. We’ve been providing servicing and installation of air conditioning in Phoenix for more than 30 years.

Air Conditioner Smells Like Urine

Does your air conditioner smell like a shady public bathroom?

How’s this for an unpleasant smell. If your air conditioner smells like urine, you are likely dealing with the mycotoxins produced by mold. This produces an ammonia-like smell that can be very strong and rather unpleasant.

Mold on its own won’t produce this odor; it’s the mycotoxins, which can actually be more harmful to breathe in than the mold itself.

What To Do About It

Follow the steps we mentioned above for giving your air conditioner a thorough clean. Given the severity of this issue, if you have a central air conditioner you’d be wise to have an expert inspect your ductwork. Mold and mycotoxins can sometimes make their way into your ducts, in which case simply cleaning the air conditioner won’t entirely solve the issue.

Air Conditioner Smells Like A Sewer

If your air conditioner smells like a sewer, there is likely a ruptured sewage line somewhere near your air conditioner or your ductwork. This results in a very unpleasant methane-like smell. High levels of methane can cause nausea, loss of consciousness, and other undesirable effects.

What To Do About It

  1. Contact your plumbing company or municipal authorities to receive guidance on investigating the possible sewage rupture.
  2. Call your HVAC servicing company for assistance with properly ridding your air conditioner and ducts of this smell.

Air Conditioner Smells Like Smoke

If your air conditioner smells like smoke, it could be one of several things.

On the severe side, you could have a fire somewhere in your home. Air conditioners circulate air throughout your home, so a fire in one room will produce smoke (and hence a smoky-smell) that then gets circulated to other parts of your home.

On the slightly less dire side, you could be dealing with an overheating motor. If your air conditioner hasn’t been adequately maintained, its bearings may have worn out. When this happens, the motor overheats and gives off a burning smell.

Lastly, your air conditioner may just be burning off some dust. This is normal; dust builds up inside your air conditioner over long periods of non-use. When you switch it back on, you’ll notice a slight burning odor for a few minutes before it dissipates.

What To Do About It

If you’re dealing with the first issue (fire in your home), your next steps should be obvious; get off your phone/computer and put the fire out or call 911!

The third issue requires no action from you. The dust will burn off on its own and the smoke smell will disappear within a few minutes.

To resolve the second issue, contact your HVAC repair company to fix the smoke coming out of the AC. They’ll need to replace your AC motor’s bearings (or whatever part has worn out). This should be an easy fix for any experienced HVAC technician.


Strange smells from your air conditioner can range in severity from dire to moderate risk. In all cases, however, strange smells warrant additional investigation. By following the steps above, you should have a clear idea of how to proceed.

If you need air conditioner replacement/installation/repair services in Phoenix, Arizona, give us at American Home Water and Air a call. We’ve been providing these services for more than 30 years and have a stellar reputation. We’ll get your air conditioner up and running — with no offensive smells — in no time!
You can also check our other articles on fixing common AC problems such as AC light blinking and many more

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