so i can turn on my fan for heat and cooling....and that works, but i cant choose where it comes out of. nomatter whether i choose feet, vent, or windsshield, it only comes out through the windshield. it also does not trigger the AC to start working

is the little **** itself busted, or is there a relay or something somewhere?

 

the vent controls are vacuum operated.

 

any ideas on where to start looking for problems then?

 

Good morning Dan.

For your problem, I would start by examining the vaccum line that goes from the engine to the HVAC vaccum reservoir (it's a black sphere, probably on your passenger side, in the engine compartment - though some are inside the fenderwell).

Remove that hose from the sphere and ensure it is pulling vaccum, engine running. If not, find the hole or break in that hose. The fitting that hose attaches to at the sphere, is a check valve. Those sometimes go bad, letting vaccum decrease inside the sphere. The sphere itself could be cracked, as well.

If all that is good, open the glovebox, push the side in and open all the way and you may find a vaccum problem in there. Worst case, is the control itself, but I'd rule out a lot before I went after that being the problem.

How's your idle? If it fluctuates a lot, it could be a gross vaccum leak in the engine, PCV hose, intake tube loose, etc, making your HVAC control problem merely a symptom.

 

cool, ill look into those things.....thanks a lot!!!!!!!!!

 

well i didnt see anything wrong with any of that....but i did replace my coolant control valve that was leaking, and now the controls work, at least for now

im not sure if that had anything to do with it, or if it was pure coincidence

 

My truck does this same exact thing...

Where can I find the coolant control valve? Did that fix the issue? Mine just all of a sudden stopped working and will only blow air through winsheild area vent. I looked behind the glovebox and didn't see anything wrong...

 

My 98 4x4 did the same thing when the PVH seals went bad, I capped the lines going to the hubs and did the "retractable pen" hub conversion, still flawless at +40,000 since.

 

the coolant control valve is a 4 port valve (on my truck, could be 2 or 3 on yours) that is located on the passenger side, not far from the firewall......it has 4 hoses and a (i think) vacuum line going into it. 2 of the hoses go through the firewall to control the coolant ot the heater core, so look for that


honestly i have no idea if this even helped.....it may just be purely a coincidence, but so far so good on my controls