Trouble switching heater outlets

[dpuckett]

On my newly acquired 92, the heater doesnt switch real strong from one setting to another- it just kind of comes out of everywhere at once. I think the defrost is good enough to pass inspection, but I'd still like a goodly blast of air to clear things up on humid/foggy mornings. Where do I look? Not sure on the vacuum- it seems only a hair less than the 91- new vac pump. Assuming that is ok, what else can I check? I had a vent door stuck, and freed it with some PB'laster. Do the vacuum modlues that open and close the doors go bad? One thing I have thought of is the control unit- I'll try the known good one from the blue one this weekend.



Help is greatly appreciated,

Daniel



PS- If I can get my girlfriend back to the shop, I promise we will post pics.

 

[bgilbert]

My 89 is somewhat the same. What I do if I want to go from defrost to heat/vent or whatever. Turn it off first. Defrost to off. Then to heat or vent. Something to do with the vacuum switching over. You can swing the glovebox out of the way and check some of the linkages and vacuum hoses. Next you'll have to remove the dash bezel, then the heater controls and check for the vacuum hose hookups there.

 

[dpuckett]

I got to troubleshooting the problem, and found I wasnt getting vacuum to the cab. Problem was at the firewall- it wasnt sealing properly. I took the whole kit-n-kaboodle out of the 90 (vacuum hook-ups, anyway), put in the 92, and it works fine now. I remembered the seller's buddy saying he had run the truck with the downpipe off, and melted a majority of the heating ducts. I got to looking at that, and sure enough, there was some melting at the grommet/ connector at the firewall. Hooked it all up and all is well.



Thanks.

DP