So I've recently noticed in my hatch ('87 Standard, no a/c) that when I turn on the heat that no only do I get great heat coming out of the heater box (or defroster) but I also get very cold outside air on my left leg. It seems to be coming out from around where the fuse box is but back more toward the fire wall (nothing comes out at the fuse box). It's getting really annoying lately and seems to have gotten worse in the past few weeks.

 

Also, the cold air increases with the speed of the heater fan just like the normal heat; when the fan is off, no cold air!

 

WTH is going on with this thing?

 

Oh, the dash vent is closed, no air comes from it or around it at all unless it is in the open position.

There is probably a hole in the intake for the climate control before the heater core. Figure out the duct set-up, and go from there.

I would check the vent door. I sounds like it is stuck in the open position.

The cable that controls the vent flap on that side has probably slipped out of it's little clip, so that you cannot fully close this flap. The cable runs just under the skin of dash edge, coming from beside the vent opening. Kind of a pain, but it can be reached and repositioned.