Scorching hot blowing air

I just had my battery replaced in my '98 Jimmy after it died today. As I'm driving away, I realized that the car was getting hot. It turns out that no matter where I have the dials set, I get extremely hot air blowing out of my vents. Air conditioning doesn't matter. Setting the temp on cold doesn't matter.

Any ideas?

Your blending door is stuck open.

Might make you laugh, but give the dash a good bang to see if it dislodges it.

Then affter that, you might have to get in there and check it out.

I bashed and bashed and bashed. (I had a lot of frustration to take out on this car!)

It didn't work.

Anyone need freshly cooked hotdogs, though?

Well, you don't have to use it as a punching bag. ;)

Your blending door is stuck or broken.