Skip navigation

Serving The Fresno & Madera Area

70th Anniversary of Purl's Sheet Metal & Air Conditioning

Serving The Fresno & Madera Area


On Call 7 Days a Week


Purl's Sheet Metal & Air Conditioning Blog

Why Does My AC Smell Strange?


An air conditioning system is not supposed to have any noticeable odor as it runs. The air from the vents should have the neutral smell of the rest of the house. If you start to detect any smell from the air vents you’ve never noticed before, such as a dirty laundry stink, rotten eggs, or an acrid burning, it’s something to pay attention to.

You may need to call our technicians for air conditioning system repair in Fresno, CA after you notice any of these odors. A few may have simple causes, but in many situations, these odors warn of a bigger problem with an AC. We’ll look into these strange air conditioning system smells and what they may mean.

Some AC Odors You Might Notice

  • Moldy, dirty laundry smell: This is the notorious “dirty sock syndrome.” That it has its own name is a good indication of how frequently it can happen. The most likely cause is that mold has started to grow inside the air conditioning system, probably across the evaporator coil. If an air conditioner isn’t effectively draining the condensate moisture that forms along the evaporator coil, it makes it easy for mold to start to grow. Mold will severely lower an AC’s efficiency—and you don’t want the odor to keep making its way around your home!
  • Electrical burning: The acrid smell of electrical burning is alarming to detect—and it’s good that it’s alarming because it can warn of a major problem with the AC. If you notice electrical burning smells from the vents when the AC is running, it may mean a motor is burning out or wires on the control panel have overheated. Shut off the AC right away and then give us a call for repairs. 
  • Dust: When you first turn on the air conditioning system for the season, you can expect to get a dusty odor. This is just build-up dust inside the ventilation system getting blown out as the AC starts work for the season. The smell should go away in an hour or less. If the smell is persistent, you may need to change the air filter or arrange to have the ductwork cleaned.
  • Rotten eggs: You’ll recognize this as the smell of sulfur, and your mind will almost immediately jump to natural gas. That’s likely what you’re smelling. Although natural gas is odorless, manufacturers put an additive, Methyl Mercaptan, into the gas so that it creates a noticeable smell to warn people of gas leaks. If your AC shares the same cabinet with a gas-powered furnace, then the reason for this odor is likely a leak from the gas line to the furnace. This is a potentially dangerous situation, so please shut off the gas to your house first, and then call the local gas company. Later, you can have our technicians take care of repairing the HVAC system.

Whenever you have doubts about the operation of your home’s air conditioning system, don’t hesitate to call our team. We’ll get to the bottom of any malfunction and have it fixed so you can enjoy your cooling system again.

Call Purl’s Sheet Metal & Air Conditioning for reliable and thorough air conditioning system repair. Uncompromised Quality & Customer Service Since 1952.

Comments are closed.