By Matthew C. Keegan

Flip on your car’s air conditioner and you expect cool, clean air to flow freely. If the AC system is producing cool air, then everything is working correctly. But what if the cool air is accompanied by a noxious smell? Likely, mold in the air conditioner is the problem and, thankfully, easily resolved. We’ll look at mold as well as other issues that may contribute to foul air inside your car.

Dirty cabin air filter

You’re familiar with the engine air filter, fuel filter and the oil filter, but did you know that your car also has a cabin air filter? Most vehicles built since 2000 have one helping to keep the cabin’s air clean, but only if the filter itself is clean.

The cabin air filter is typically found inside your vehicle’s glove box or it may be located under the dashboard or hood. Reference the owner’s manual to pinpoint its location. When you find the cabin air filter, remove and inspect it. If it’s dirty or clogged, then it may be causing the foul smell. Simply replace the filter with a new one. The mold smell may immediately disappear.

AC unit drain tube

Just like your home’s air conditioner unit, your car’s AC system has a drain tube. If that tube becomes clogged, water may back up. And just like a river, water will find the path of least resistance and come out some other way, as in your dashboard, where it may attract mold and bacteria, causing damage to your car.

Find the air conditioner drain tube and detach it. A metal wire inserted inside same is useful for freeing gunk. Reattach the tube, then look for signs inside your car where water is gathering. Wipe up the water and be sure to disinfect to remove potential bacteria and viruses.

If gas is the odor

So far, we’ve looked at mold in the air conditioner as the problem. But what if some other odor is detected? In particular, a gas or oily smell may become evident, especially when the AC is turned on its highest setting. All that noxious air pouring into the cabin — no wonder you feel lightheaded or sick to your stomach!

Here, you’ll need to check several components one by one to locate the source of the smell. The fuel pressure regulator may be leaking or the fuel injector “O” rings may be dripping gas. Be sure to check the exhaust system as well, as potentially deadly fumes might fill your cabin.

Other areas

If your cooling system has sprung a leak, you’ll soon detect a sweet smell of coolant entering the cabin. Inspect the entire cooling system for signs of leakage and where repairs may be needed.

Other odors may intrude from time to time, so carefully inspect under the hood to remove foreign objects, including twigs, leaves and road debris. Such objects coupled with the heat from your engine can create a new set of odors.

Finally, keep the air vents clean by wiping between the slats. A cotton swab can reach into small areas, removing debris and potential odor causing agents.

For more information on mold in the air conditioner, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.