Posted on 1/30/2026
That musty A/C smell usually shows up at the worst moment. You start the car, the air kicks on, and for the first few seconds, it smells like a damp gym bag. Then it fades, and you wonder if it’s even worth dealing with. It is, mostly because the smell is often a sign that moisture is hanging around in the HVAC box, and moisture tends to bring friends like mildew and bacteria. The good news is that this issue is usually fixable without turning the car upside down. The key is understanding why it happens and what actually works, not just masking it with a stronger air freshener. Why The Smell Shows Up After Summer During summer, your A/C is pulling humidity out of the air all the time. That moisture collects on the evaporator core, and it’s supposed to drain out through a small drain tube under the vehicle. If the evaporator stays damp for long periods, or if the drain doesn’t flow well, you get that stale, musty smell. Heat and humidity speed the ... read more