heat coming out of the vents?

[lost86broncoii]

When my truck gets run to temp, doesn't over heat , heat comes through the vents almost like i had my heater running, there always seems to be air blowing through my vents too.. not alot of air like the blower was stuck on high, but enough to notice... any one know what would cause this?

 

[BlackBII]

It's an RBV thing.

Blend door is not shutting off the hott side. This one has been covered before, do a search.

 

[lost86broncoii]

Blend door... thanks, searching now