7 Ways to Fix Smelly AC Vents

Does your vehicle’s air conditioning smell like dirty gym socks?

Unfortunately, the heater ventilation air conditioning (HVAC) system builds up moisture, mold, and mildew in its evaporator and ductwork. That moisture is the culprit. But here are seven ways to get rid of that lousy car AC smell—and get your HVAC system smelling sweet.

Clear the Drain Hose

Your vehicle’s HVAC system has a drain hose that collects and removes condensation from the AC system. That’s why you’ll often see a small puddle of water under your car after using the air conditioning. If that tube gets clogged, it can produce a swamp-like car AC smell (or the water can spill out in undesirable and harmful places).

Most heat and AC systems sit under the dashboard in the passenger footwell. Look for a half-inch rubber hose attached to the bottom of a large rectangular box near the firewall.

Place a towel or cup under the hose connection and gently remove the tube to check for a clogged outlet. Be advised: If moisture builds up, water could come gushing out. The main goal is to ensure the hose is not clogged and is working as intended so the water freely drains to the pavement. Next, run a wire up the hose to ensure nothing is plugging it. This first step is crucial.

Sanitize the System

Get straight to the source when your AC smells terrible. The chief task is to clean out and sanitize the inside of the HVAC system. We recommend using a duct cleaner and deodorizing spray. These aerosol-foaming cleaners are designed to be sprayed into your vehicle’s vents and through the drain hose.

• Spray the foam into the ducts until it fills the vents.
• Inject some foam into the drain hose.
• Let the foam soak in for about 30 minutes, breaking down and draining out of the HVAC system.
• Park the vehicle in direct sunlight. Heat helps the process.

Now, start your vehicle and run the air conditioner at max speed for about five minutes to dry the inside of the system. Then, it’s time to take a whiff. If the smell is still there, repeat the process.

Disinfect Every Six Months

After your HVAC system is clean and sanitized, you can keep things smelling nice. Do this by spraying Lysol or a specialty disinfectant into the air vents and intakes every six months:

Spraying a disinfectant into your car’s AC and heat system can stop smells before they start.

• Start your vehicle.
• Turn on the HVAC, setting the temperature to low.
• Make sure the air intake’s set to recirculate the cabin air.
• Spray the disinfectant into the passenger footwell for about 30 seconds so that it gets pulled into the HVAC system.
• Repeat this process with the HVAC temperature set to high.

Following these steps, the HVAC system’s heater and air conditioner parts will be disinfected and cleaned.

Replace Your Cabin Air Filters

Remember to replace your vehicle’s cabin air filter during routine maintenance, or at least every 15,000 miles. A cabin air filter traps grime, including dirt, dust mites, and harmful pollutants. It is usually near the glove box and can be easily replaced.

Turn on the Fan Periodically

We recommend periodically turning on your AC fan, leaving the AC and heat off, and letting it run for a mile. This will allow the inside of the HVAC system to dry out and prevent bad smells.

Use a High-Quality Air Purifier or Deodorizer

Clear out other interior smells using a high-quality air freshener or deodorizer. For chronic odor problems, place a plug-in air purifier in your vehicle. These filters plug into a 12-volt accessory plug and use particulate absorbers and ionizers to clean the air.

Turn Off the AC Stopping the Vehicle

When using the air conditioner, we suggest turning it off a mile or so before your final stop. This allows time for the system to dry.

Related: Why Does My Car Smell Like Eggs, Crayons or Other Odd Things?