You may have noticed sometimes on a hot and humid day, vapor will come out of your vehicle's vents when you have the air conditioning on.  Is that something to be concerned about? Well, it depends.

Sometimes that steam or vapor can be caused by water accumulating in the vent system after it has condensed.  And sometimes water can pool at the bottom of a vent.  When you turn on the blower mower, the air hits the water and may create steam or vapor that you can see in the cabin.

One thing to check is if that vapor smells like anything.  If it doesn't, that's a good sign. You may be able to run the fan for a while and the issue may just go away when things dry out.  But moisture collecting in the ventilation hoses in a hot vehicle may be a breeding ground for mold, and that can have health consequences.

There's another possibility. Ventilation systems often have drains to get rid of any accumulated water, and debris can sometimes clog them.  A technician can clean out those drains and you'll be back in business.

One thing to nose around for is a sweet smell coming out of your vents.  Sometimes the heater core (a component of your vehicle's heater system) can develop very tiny holes.  That sweet smell may be coolant that's been vaporized by those tiny holes entering your cabin. 

It's always a good thing to mention to your service advisor any abnormality you're seeing—or smelling—in your vehicle.  By venting a little about your vents, a technician can get to the bottom of the problem before it starts "clouding" the issue.

Auto Lab Troy
2790 West Maple Rd.
Troy, Michigan 48084
(248) 643-7690