When I turn on the vent in my car, there's a horrible musty smell. What can I do?

Question

I drive an '05 Hyundai Elantra. When I turn on the vent in my car, there's a horrible musty smell. When the AC is on, it stinks at first, but then the smell dimenishes. My husband took out the AC filter and cleaned it out...it did not smell. However, that didn't seem to help. I don't want to pay a mechanic to tear my AC/vent system apart if it's an easy fix. Should we just replace the AC filter? Could it be another filter or something else completely? Thanks!

Answer 1

As a quick fix you can get one of those air fresheners that attach to your vent and work when you turn on the AC/vent.  I have one in my car, and it always smells nice.  

Answer 2

This is a simple explanation.  The moisture within your A/C system is a breeding ground for bacteria; when certain types of bacteria form on the evaporator, inside your a/c system, that bacteria emits the smell you are describing. This is a very common problem, not rare at all.

The solution to the problem is to apply a disinfectant to the evaporator; the difficulty is, however, how to physically insert the disinfectant. Its not easy without professional help.

A/C mechanics who understand this problem can drill a hole, behind the glove box & then use a wand attached to a presssurized container, to dispense the disinfectant (aerosolized is best). The disinfectant needs to be foamy, so that it travels around the exterior of the evaporator...  all the liquid will eventually flow through the A/C drain hose, onto the ground....

Many A/C techs will not have the tooling to perform this job; they will steer you to something that they are capable of instead.  

My former company, Petor Chemical Products, used to make an aerosol that you spray updward through the a/c drain hose but the problem is some car types, don't have the hoses (some Fords).  Sadly, my company was bought by a low class, nearly bankrupt competitor who sells only low end products.

Answer 3

Might be mold or mildew on the evaporator coils or excess condensation being trapped elsewhere.  Clear out debris from the HVAC intake, usually on the passenger side cowl under the hood.

Answer 4

My Honda Civic used to have this problem but it eventually went away with more use. Either that or my lungs are used to it that I no longer smell it. I think the smell usually comes from the engine unless of course there are some very noticeable reason in the environment. How often do you use your AC? Sometimes it can happen when you don't use it as often.

Answer 5

do you leave your vents on when you turn off you car? Make sure to turn off your vents and change your temperature setting to the center when you shut off your car that is what helped for me

Answer 6

Is there water dripping from or around the right front wheel area? If not the drain is plugged up and all the water just sits in the air box. Dripping water is normal btw. Just like a musty basement smell.