My AC smells like mildew when I turn it on
A musty smell is usually mold growing on the evaporator, the cold part hidden in the dash, plus a dirty cabin air filter. Miami humidity keeps it wet, so it grows fast. A sweet smell is different and can mean a coolant leak inside the dash.
Urgency
This week is fine
What to do right now
What to do right now
- 1Check if the passenger floor carpet is wet. A clogged AC drain lets water back up inside.
- 2Look under a parked car on a hot day. You should see water dripping under the passenger side. No drip can mean a clogged drain.
- 3Turn off the AC and run just the fan for the last few minutes of your drive to help dry things out.
- 4If the smell is sweet and the windows fog up greasy, get it checked soon.
What it usually is
What it usually is
Questions people ask
Why does my AC smell like old socks?
That is mold and bacteria on the evaporator. It stays damp from humidity and condensation. Cleaning it and changing the cabin filter usually fixes it.
How often should the cabin air filter be changed?
In Miami, at least once a year, and more if you drive in heavy traffic or with the windows down. A clogged one also weakens airflow.
Is the smell bad for me?
Mold in the vents can bother people with allergies or asthma. If anyone in the car gets stuffy or coughs when the AC runs, do not wait.
My car smells like vinegar when I start the AC. Is that normal?
A vinegar or sour smell is usually the same mold issue. It is common in humid places. A cleaning takes care of it.