How to get a mildew smell out of car vents? locate the hose that leads up to the evaporator drain pan, clean any mud or debris from the drain hose end.

If ac blows air that has a mildew odor, the problem could be the drain pan of AC's evaporator unit is not draining and causes a mildew smell in the car vents.

Possible cause of mildew smell in the car vents

(1) AC evaporator unit is not draining.

Car Troubleshooting

First, we will need a little background information in order to understand what's going on here... A key component of an A/C system is the evaporator. While the A/C is on, the evaporator gets very cold. Air is then blown through the evaporator's many fins, thus causing the air coming out the A/C vents to be cold. On hot and humid days, condensation forms on the evaporator (since it's cold). This condensation/moisture drips down to the drain pan of the evaporator unit. Normally, this condensation is funneled down a hose and onto the street. Now, back to the problem at hand... air conditioner smells musty.

If the drain pan isn't draining (due to a clog somewhere), moisture will get trapped in it (i.e. the drain pan). Such moisture breeds the growth of algae-like organisms, which tend to give off a mildew odor. This odor works its way up to the evaporator and is then blown out the vents (which is when you smell it car ac smells musty.

How to Get Mildew Smell Out of Car Vents

Crawl under the car and locate the hose which leads up to the evaporator drain pan. Refer to a manual covering your car model if you need help in finding it. Once you locate the drain hose, clean any mud or debris from its end. However, if the end of the hose isn't clogged with mud/debris, the clog must either be further up the hose or else in the base of the drain pan. In this case, you'll probably need the assistance of a professional in order to locate and clean the clog/blockage.

How to Unclog Your Car AC Drain Line

Video credit

Once the drain pan is again draining properly, it will take at least a couple of days for the algae-like organisms to dry up, and thus the mildew smell in car AC to go away.

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