Strange odors are a symptom that will put any Inland Empire homeowner on alert, especially when a home’s air conditioner smells bad when it’s turned on. The blast of cool air you feel when your air conditioner starts up should be the only thing you’re hit with – a sudden wave of stench is out of the ordinary. Learn what it means when your air conditioner emits unpleasant smells upon startup and what to do to avoid them in the future.

Mold and Mildew Odors

If the air conditioner smells bad when it’s turned on, homeowners most commonly complain about an odor of mold or a mildew smell. This unpleasant odor can stem from a few different sources within the cooling system.

Moldy Coils 

The evaporator coil sits within the indoor component of your cooling system, whether it be a furnace or air handler. Condensation naturally results as these coils pull heat and moisture from the air during the cooling process. When everything is operating as it should, the condensation flows away from the coil and is drained out of the system.

If there is a lot of dust and dirt accumulation on the coil, these debris combined with moisture can facilitate mold growth. The evaporator coil usually becomes excessively dirty due to infrequent maintenance. 

If you notice your air conditioner smells bad like dirty socks when turned on, you can check the evaporator coil for mold growth by removing the access panel on the indoor unit’s cabinet and take a peek. If you see mold, call your HVAC technician to fix the problem by cleaning the coils with appropriate cleaners. Change the air filter on a regular basis to keep excess dust and dirt out of the system. Make sure to schedule annual maintenance for your air conditioner, which includes service for the evaporator coil.

Moldy Filter

Moldy filters can be the cause if your air conditioner smells bad when it’s turned on. Just like with the evaporator coil, excess dirt and dust can cause mold to develop in this area. Failing to change the filter regularly keeps more debris inside the unit, and any moisture introduced to the filter can create a breeding ground. 

Inspect the filter, and replace it if you notice mold on its surface or if the filter is filled with contaminants. Make sure to change the filter regularly throughout the year. 

Burning Smell

While a brief burning odor is normal when your furnace turns on for the first time each year, burning odors are not normal during other times of the summer. There should be nothing burning within your cooling system, as the air conditioner does not burn fuel to operate like a gas furnace does.

If you notice a burning odor, turn off the air conditioner. Check around the house to see if there is another source responsible for the odor such as cigarette smoke. If not, keep the system off and call for AC repairs.

Garbage or Rotten Egg Smell

If your AC smells like rotten eggs or garbage, these are telltale signs of a dead animal somewhere inside your HVAC system. Rodents and vermin can climb into outdoor condenser units looking for winter shelter, as well as to find ways to access your ductwork. If they die within your equipment, eventually you’ll experience the odor of decomposition in your home.

If you can find the location of the carcass, you may be able to remove it yourself. If you are not comfortable doing so or cannot access the dead animal, call for professional help. Your technician can clean out the air conditioner or ductwork if necessary, as well as identify and repair any damage caused by dead animals.

Get Help with AC Smells

If your air conditioner smells like any of the bad odors we mentioned when it’s turned on, turn to Sanborn’s for the help you need to eliminate the foul odor coming from your air conditioning system. A bad AC smell can quickly spoil your summer day. Our technicians correct your system issues and care for your air conditioner to prevent further issues. If you are in need of air conditioner repair or maintenance, contact us today.