I've been working on getting my heater working on my 90. I cut the box and cleaned it out according to the sticky. Pulled the cover off above the tranny hump and cleaned that out. Emery clothed the cable from the controls to the blend door and lubed it up, so it's free now.

I can't get the blend door to move all the way. It moves a bit, but not the full range. I'm thinking about just cutting another access hole in the box to get to it and figure it out, but thought I'd check here if anyone had any ideas first.

Thanks

 

I have seen the various air door hinge pins rust and sieze in the bottom of the box thus preventing their movement.

 

Maybe I can drip some penetrating oil down it and see if that helps. The control cable was rusted on the exposed areas, so that could be the case.

 

open the glove box all the way so you can reach behind it. The control rod towards the right opens and closes that door. with the engine off, see how easily you can manually move the rod. then start the engine and see if both vac lines have some vacuum.

 

I've already got the glove box off. The one I'm talking about isn't the vacuum operated doors. It's the hot/cold blend ran off the pull cable on the left side behind the glove box. It doesn't have a vacuum assist on it does it?

I've got some stuff apart on the motor, so I can't start it right now, but will check vacuum once I get it put back together.

 

Ahh my mistake sorry. Could the cable have sliped in the pinch bracket that holds it to the arm behind the glovebox? Have you tried to "zero" it by turning the HVAC all the way to cold, and readjusting the slide cable? then swing it to hot and see if you have proper travel

 

The weatherstripping may have started deteriorating. That's what happened to mine. I think I really need to pull the whole assembly out of the truck, but I really never have had the time. I tried to clean it up and put new in there, but it is a pretty tight space to work in from the engine compartment. lol

 

I've got plenty of cable. It's completely free. Hooking it back on the arm, I can only move the lever on the controls maybe halfway. That's where the arm binds up, but I still have travel left on the cable.

 

I haven't got that far, but can you pull the blower motor and see inside to that door from the engine compartment?