When you turn on your AC, does it produce a weird odour? If this is the case, there definitely is a problem.
Fortunately it’s fairly common and is caused by a variety of issues, which we will address in our guide to bad air conditioning smells.
Mold and Bacteria Growth
The most common reason for foul smells produced by your cars AC is mold/bacteria growth. Air conditioning works by removing heat and moisture out of the air that’s already in your car, resulting in a nice cold breeze.
The side effect of this moisture removal is an ideal place for mold to grow, causing bad smells and potential health implications.
How to get rid of mold
Fortunately getting rid of the mold is straightforward. There are several methods of treatment, fortunately they aren’t too expensive.
Sometimes a dirty air filter can trap bad smells, pushing them back through your vents. Fortunately it’s a straightforward change, and cheap too. Using a Haynes Manual (https://haynes.com) will show you how to change your filter easily.
This filter should be changed according to your maintenance schedule, which you’ll find in the service book supplied with your vehicle or applicable Haynes Manual.
Killing bacteria that’s grown in the intake ducting, or the condenser will eliminate bad smells. Condensation that builds up from cooling air is usually drained away, however if the system doesn’t get a chance to dry out, mildew can grow throughout the system causing unpleasant odours.
Turtle Wax Whole Car Blast is the product I've used to get results, which is an easy and cheap way to de-smell your cars HVAC system.
Step 1: First place the canister into the passenger’s foot well, nozzle facing upright.
Step 2: Next turn the car and air conditioning on, with the fan speed on full in recirculation mode.
Step 3: Depress the button on the can, which will release a continuous stream of spray. Shut the doors and windows on the vehicle and let the spray circulate around the HVAC system. This should take between 10-20 minutes.
Step 4: Keep the fans blowing full speed with the AC now switched off, for five minutes. Ensure the doors/windows are open – this is to dry out the whole system, preventing odours from re-establishing themselves.
An alternative to anti-bacterial spray is an ozone generator, which will kill all odours in the AC system. If all else fails this is one of the most effective way to eliminate the source of bad odours, and can get in every crevice ensuring complete cleaning.
Ozone isn’t safe to breathe in, therefore precautions should be taken to avoid contact with the produced gas.
To get started:
Step 1: Turn the car on, and ensure the air conditioning is set to full fan speed and recirculation mode, with the temperature as low as possible.
Step 2: Set the Ozone generator to work for 20 minutes, our generator outputs 5g/hr – if your machine outputs more, adjust the time accordingly. Overexposure can cause damage to interior rubber!
Step 3: Turn the vehicle off and allow it to ventilate for an hour or two. Be careful not to breathe any of the ozone gas in, as it can cause respiratory irritation.
Due to the complexity of a car’s HVAC system, there are multiple reasons why you may smell burning rubber.
Burning off Dust
If you haven’t used your AC in a while, dust and other debris can build up all over the system. When your HVAC system gets up to temperature, this debris will be burnt off releasing a burning odour.
If you still notice the smell after a few minutes, it may be a different problem and should be investigated immediately.
Clogged Air Filter
Despite being a maintenance item sometimes an excessive amount of particulate can build up in your filter, severely reducing airflow. This will put extra strain on the rest of the components, commonly producing a burning rubber smell.
To rectify this issue, changing your filter will immediately get rid of any unpleasant smells. In all cars they’re accessible and can be changed using tools you have around the house! I recommend using a Haynes Manual if you’re unsure how to get started.