All right so it's starting to get cold. A few days ago I get into my truck and turn on the heat. At first there was nothing which is normal as it takes time to heat up. About 20 minutes into my commute only like warm air which is weird seeing as how this thing normally blasts heat. Then a creaking noise which sounded like it was coming from the dash happened and then heat starting blasting. After a minute it went back to Luke warm air. I've noticed when a significant change in speed occurs the creaking noise happens and heat begins to blast again. Anyone have any ideas?

 

vacuum leak, cracked vacuum hose in heat circuit, stuck blend door are the first things i would look for.

 

Where is the blender door located? I've looked online and found nothing

 

inside the heater box.

 

I believe it would be about the same as my 96.
First you need to remove the glove box. The next thing is the plenum box which is behind the glove box. Once that is out, the blend door will be below where the plenum box was....Been awhile since I had mine taken apart and I do not look forward to ever having to do it again.