Why does my AC in my car smell musty

These smells are usually due to dirt, dust and debris buildup in the under-hood air intake vent, trapping water and moisture on the AC evaporator and in the evaporator case. All kinds of nasty gunk (germs, mold, mildew) can fester and grow in that wet, trapped debris.

How do I get the mildew smell out of my car air conditioner?

Spray an antiseptic into the exterior air vents (where your car pulls air from outside into the car from). Be sure your AC is set to the setting that pulls air from outside in, so that the spray is pulled into the ventilation system and can directly work at killing of mold and bacteria.

Why does my car air conditioner smell musty when I turn it on?

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.