Skip navigation

Serving The Chicagoland Area Since 1998


ServiceMax Blog

AC Odors? Your Air Conditioner Needs Repair


This is a very simple truth: your air conditioner should not smell like anything. AC odors are not normal, and if you ever detect any type of odor from your AC, that is a sign of a problem which most likely requires repair.

Why would an air conditioner start to smell? What might it smell like? What could be wrong? We’ve got some answers for you.


This is an odor you’re familiar with. If you smell that old, damp, musty smell, like a basement that has never been truly aired out, you can be sure there’s mold growing somewhere. But where would mold grow in an air conditioner? There are two possibilities.

First, there’s the condensate pan. This is where moisture gathers as it drips from the condensation on the evaporator coils. It flows out a drain and away from your house so it won’t cause water damage. But if you didn’t have it cleaned this spring (part of routine maintenance) it will create a great environment for mold to grow. If this is the case, the smell will be strongest close to the indoor AC unit.

Alternately, the problem could be in your ductwork. If any moisture has managed to pool in there, the dark, enclosed space is also a wonderful home for a mold colony. Instead of AC repair, you might need duct cleaning. If this is the case, the smell will be strongest close to one or more of your HVAC vents.


Either of these places can also grow bacteria in stagnant water. This may smell sour like vinegar, or rotten like garbage. Again, you may be able to tell what the location is by where the smell is strongest. Either way, you need the help of a qualified HVAC professional.


Overheating AC components can cause huge problems. This can include short cycling, when the system shuts down from excess heat and starts up again right away, using a ton of extra energy, driving your electric bill up, and straining the compressor. It can also include the wiring in the motor becoming actually fused together from heat! This will necessitate a whole new motor.

If you smell hot metal, burning dust, or melting plastic, something in your air conditioner is overheating. It’s most likely to be the blower fan motor. Turn the system off! You definitely don’t want it getting any hotter. You need AC repair in Skokie, IL.


One final warning: an electrical fire produces ammonia. This means it can make an odor like fish, because dead fish also release ammonia. If you smell this, turn off the system immediately and don’t turn it back on until it’s been repaired. It’s simply not worth the risk to you, your home, and your family. 

Take any AC odors seriously and have them repaired promptly. If you have any concerns about your air conditioner or your ducts, we’d be delighted to hear from you.

Contact ServiceMax with any questions about your air conditioner or your ducts.

Comments are closed.