Ideas why I'm getting hot air through vents on car?

[gensetsteve]

Our last two discoveries did this had the aircon on to counteract the heat from the transmission tunnel and defective heater. Not sure if all vehicles use flaps or some have may still use a motorised valve but something may be just out of adjustment.

[WeFixIt]

I had one of these buses a few years back

Every time you start it up you could here the heater hot/cold flap open and close

Can't remember now which it was at when off ?

 

Nearly all cars have a small draft air flow some using the fan at a very slow speed to insure good ventilation