Weird Car Air Conditioner Smell: What It Means and How to Fix it

January 27, 2012

When you turn on the air conditioner in your car, do you often have a distinct car air conditioner smell that is weird or repugnant? If this is the case, then there is definitely wrong with your car air conditioner.

There are some ways to detect and find certain smells that are coming from your air conditioner. Most of the time, these smells are a result of some damage in your car air conditioner. There are also several reasons why your car air conditioner emits a certain smell.

Mold and Bacteria

Probably one of the reasons why there is a distinct smell in your air conditioner when you turn it on is the growth of mold in your air vents. Smells of mildew in your car may be caused by the growth of bacteria.

As the car becomes older, bacteria, mold, fungi, and micro-organisms can start to grow. The growth of these bacteria is often behind the dash panel on the evaporator. This causes an unpleasant odor coming out the air conditioner unit. Also, if the air conditioner is not used as often then this can also cause the growth of bacteria.

Turning on your air conditioner to maximum often may also cause bacteria growth due to the excess water that is dripping in your unit.

To fix this problem, locate the drain tube in your A/C unit. Make sure that is working properly. Use an anti-bacterial treatment that will destroy bacteria that is growing behind your dash panel. Inject the treatment solution into the air conditioner case. It is advisable to turn off the car air conditioner for awhile and let the fan run instead for a few minutes. This will help evaporate the water on the coils of your unit.

Gas Leak

If you smell gas every time you turn on your car air conditioner, then your car may have a gas leak. When you turn on your A/C unit, the gas smell is being sucked into the fresh air that the air conditioner is taking.

To solve this problem, you need to repair the leak. There are several areas where you can check for a gas leak. Inspect the fuel pressure regulator of your engine to see if the leak is in this area. You can also check the fuel injector "O" rings in the engine compartment for any leaks. It is also advisable to check your exhaust pipes and muffler for any holes that can cause gas leaks.

Dirty Air Filters

Your air filters may also be causing a weird car air conditioner smell. If not cleaned properly, the air filter can collect dirt, stagnant water, dust mites, and other harmful pollutants. This can result in a bad smell every time you turn on your air conditioner. You can easily fix this problem by just replacing the old filter with a new one and regularly cleaning the air filter of your air conditioner unit.


If the cooling system in your car smells sweet, then you should have your unit checked immediately. The sweet smell is often the cause of toxic liquid ethylene glycol or antifreeze. This smell is the result of a leak in the cooling system. The leak can come from the heater core, pipe or hose, coolant housing unit, or the radiator.

Related Questions and Answers

What is the Average Cost of an A/C Anti Bacterial Treatment?

You can do an anti bacterial treatment for your A/C by yourself. There are special antibacterial cleaners that you have to spray on the air filter once a month. You can also try cleaning your air conditioner at least once in a month to ensure that it produces clean and filtered air. Try products like Klima-Cleaner's. This product removes odors from the car and removes water condensation on the air conditioner system too. This can cost about $15 per bottle and can last you a long time. Other products you can try include GardX One Shot Deodoriser, and Kleen Air-Air Conditioning Cleaner & Purifier. Both of which cost about $45-$100.What Can I Expect to Pay for Replacing the Fuel Injector O-Ring?

A fuel injector o-ring is usually sold at car spare part stores. The dealer may try to sell you the entire fuel injection system, as a few cars will come only in sets. Take a look at the Owners Manual to find out the size of the o-ring that you require. You can then ask the dealer to show you an assortment of rings and then choose the right one from them. The average cost of an o-ring will be about $15 for a set of four. For example, the Felpro Fuel Injector O-Ring comes for $13-$15. You can do the replacement yourself or you can get a service shop to do the job for you. Service shops will charge differing amounts depending on the job that was done.How Much Does a New Air Filter Cost?

Most car manufacturers will recommend that you install a new car filter every 5,000 to 10,000 miles. But you can use reusable filters too that are present on the market. For example, K&N has several great quality reusable filters that are washable and reusable. These cost anywhere from $40-$200. But these high quality filters are made of surgical cotton gauze. You will also find ordinary air filters made of paper, which are supposed to be disposed after use. These are cheap and cost about $20-$45. Check with the owners manual to find the right air filter model that you require.

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