It’s the first really hot day and you’ve enjoyed all you can stand; gas mileage be damned, you’re going to turn the A/C on!
So you crank up the A/C and… wait, what’s that smell? Smells like something crawled into the A/C ducts and died. It’s really rank!
Car Dirty Sock Syndrome
That air conditioner bad smell — well, it could be a dead animal, but more likely it’s alive… live mold and mildew that’s begun to grown in your air conditioning evaporator. Here’s what happens: 
A big part of the air conditioner’s job is to remove moisture from the incoming air. It does that by lowering the evaporator temperature. The moist, hot air passes over the cool evaporator and the moisture condenses. That’s where all that water’s from that runs out from under the car when you run the A/C.
That water is supposed to run out from under the car. But in some cars, a little water remains in the evaporator. Maybe it’s because the evaporator tray isn’t angled right or maybe a leaf got down in the housing and it’s blocking the drain.
Whatever the reason, there’s water pooling in the evaporator, and it’s created the perfect environment for mold and mildew to grow. That’s what you’re smelling. This process is also known as dirty sock syndrome.
Of course, if it were just the odor, you might be able to get used to it. But that mold and mildew is actually eating away at your evaporator. Eventually it’ll work its way through, killing the A/C entirely. You’ll have to spend big bucks to get it fixed or learn to live without air conditioning entirely.
Fixing The Bad Smell In Your AC
So what do you do? You can’t drive without air conditioning; that’d be barbaric. But what choice do you have?
You can take your car to your local Cottman center. They offer a special service where they spray a special cleaner onto the evaporator. It kills the mold and mildew, protecting the evaporator while it leaves the air conditioner with a fresh, clean scent.
So don’t hold your nose: Call your local Cottman center and tell them your A/C stinks! They’ll know just what to do.