8 Bad Air Conditioner Unit Smells & What To Do About It

It’s summertime, and the weather is…. hot. Your air conditioner is running, and you’re craving that sweet coolness on your skin, but there’s a nasty smell. What’s causing it? And how do you get rid of it? Here’s our list of 9 common bad smells and a solution for each one.

1. Dirty Socks

Ahh the smell of dirty socks. Or worse yet, funky feet. Yuk. That’s the smell that develops when standing water or bacteria growth in your air conditioner is running amuck. The good news is, it may smell bad, but it’s usually not harmful.

WHAT TO DO: First, change your air filter if it is wet or clogged. Then, call us to come clean out your AC system, especially the evaporator coil and the drain. Ideally this should be done annually.

2. Rotten Eggs

This is worse than it smells. AC units that smell like rotten eggs or sulfur usually means one thing: there’s a gas leak in your house. This could get into your ductwork and its hazardous – in more ways than one.

WHAT TO DO: Turn off the gas supply ASAP if you can do so safely and have everyone leave the house. Then call 911 or your gas company to report the leak.

3. Musty Mildew

Extra dampness in your air conditioning is moisture that escapes via the airflow. It can get trapped in the ducts, creating mold and mildew growth in the ductwork, and thus that musty mildew smell.

WHAT TO DO: Check your AC filter for moisture or blockage and call an HVAC pro to clear out your condensate line ductwork.

4. Burning

If that sight smell of something burning happens when you turn on your HVAC, its mostly nothing serious. But if it’s a strong burnt odor or smells like gunpowder, it could mean there’s an electrical fire hazard – a short circuit, motor overheating or frayed wiring.

WHAT TO DO: If it’s faint, wait a few minutes and see if it disappears on its own. If it’s strong, switch off the system, evacuate your home, and call the fire department from outside. Once the situation has been stabilized, contact us to repair or replace your air conditioner.

5. Exhaust Fumes

Exhaust is not a smell you want your powered AC to emit. This usually happens when burning fossil fuel such as gasoline. Exhaust fumes means there could be a leak in your refrigerant line or motor.

WHAT TO DO: Turn off the system and get emergent AC repair.

6. Vehicle Coolant

Antifreeze, a significant ingredient of vehicle coolant, smells sweet – like Freon. Unfortunately, Freon or R-22 is a toxic residential AC refrigerant that’s in the process of being phased out by the government. If you smell this, you could have a Freon leak which is dangerous if inhaled.

WHAT TO DO: Stop running the air-con and open the windows wide to let in the fresh air. After that, call us to find and fix the leak.

7. Cigarette Smoke

If you’re a smoker, you’re going to smell the scent of cigarettes coming from you’re AC unit. The stale smoke is absorbed by your HVAC air filter and the evaporator coil and then “recycled” throughout your home.

WHAT TO DO: Make a habit of changing or cleaning the filter every 30 days and having the system expertly cleaned at least once a year. Quitting smoking (at least indoors) also helps.

8. Garbage

A nasty garbage-like smell usually means that a rodent, bird, or other creature made it into your ductwork and died there. Running the air conditioning is helping to spread the smell in your house.

WHAT TO DO: You’ll need to hire someone to remove the animal’s remains and clean your duct system. Until then, limit the spread by not using the air conditioner.

Keep Your AC Clean & Safe

If you have a question about air conditioner smells or other HVAC issues, don’t hesitate to contact us. Our team of trained technicians will clean, repair, or replace your air conditioning in the GTA.