When you turn on your air conditioning, foul odors can take you by surprise. Unfortunately, various HVAC issues can cause the air coming from your vents to smell like anything from old socks to car exhaust. Below are a few reasons for this and when you should call an HVAC contractor for assistance.

What AC Smells Should You Pay Attention To?

1. Car Exhaust

Your air conditioning contains coolant and lubricant for the motor, so a leak can smell like car exhaust. In most cases, this is caused by a broken refrigerant line leaking fluid onto the motor housing.

Over time, a refrigerant leak can cause your outdoor condenser unit to freeze up. This not only damages essential components but also means that the warm air your AC collects can't interact directly with the evaporator coils that help cool it. As a result, your house will be uncomfortably warm. Finding and repairing these leaks usually requires the expertise of a skilled HVAC contractor.

HVAC contractor

2. Mold or Old Socks

As your AC works to cool down your home, moisture from the air collects on cold surfaces and drips down into a drain pan. The condensation should then drain safely out of the house, but the line can often get clogged by algae or debris.

Standing water anywhere in the AC system can trigger the growth of bacteria and mold, which can create smells much like old, dirty socks. Fortunately, clearing out the drainage system is a relatively simple repair that can remove these unpleasant odors.

3. Burning Smells

A modern AC system contains several components that involve complex circuitry. If you smell an odor like burning plastic or rubber when your AC comes on that does not fade after a few minutes, chances are there is a shortage in its electrical system.

A loose wire or damaged component can eventually damage your AC system and may even cause a fire. If you smell burning, shut off your air conditioner and call an HVAC contractor immediately.


Whether the air coming from your AC vent has a strange odor or you need a complete system replacement, SG Services will provide exceptional service and reliable results. Their highly-trained, experienced HVAC contractors have been serving Centennial, CO, homes and businesses for years, using only the most advanced equipment in the industry. Visit their website for more on their AC services, follow their Facebook for tips and advice, or call (720) 435-3031 to schedule an appointment.