Noticed an odd little problem last night on my 01 D2; if I turn the climate control completely off I get warm air from my upper registers. Before I dig into the RAVE and the dash has anyone run into the same issue? If so, what did you find?

 

I feel some heat from all the front registers all the time (I never use the AC). Is it blowing out or just leaking out?

 

I think that's normal, my truck does the same. Even with the climate control completely turned off, the system still operates some functions behind your back. One them is to pop open the fresh air flap when the truck is moving faster than around 17mph.

What I suspect is going on is that, even though the heater control is turned off, there is still heated coolant flowing through the heater core and, consequently, radiates heat into the air disto box. That in turn heats the air flowing through the box by virtue of the vehicle's speed since it automatically opened the fresh air flap.

 

That is perfectly normal for all cars, when the HVAC system is off you are getting ram air into the ventilation system from the forward movement of the car.
The warm air you feel is outside air.
Try this in the dead of winter and you will get cold air.

 

Yep. I'm a goober. Tested it today (much cooler) and guess what? Air about the temperature of outside came from the vents. Clearly normal.

I guess I hadn't noticed that on any of my other vehicles. On my GMC truck if you ever turned the whole system off you wouldn't get anything out of the vents. Same with my wife's MB.

Good news: one less thing to fix.

 

I've found if I turn the temps all the way down to low before i shut off the climate control i get far less air leaking by.

 

damm, you beat me to it...i do the same thing....whatever does escape the registers is actually colder than ambient.