Been having an issue with the hvac system my 1993 d250. Google was no help, so figured I'd post here, hopefully this hasn't been answered already.

Anyways, this is a relatively new issue (past 3 months), I'll start the truck up, blower will run just fine. But after a number of minutes (it varies, sometimes 5 minutes, sometimes 30) the blower will shut off. When it goes, so does the ac compressor. Sometimes, it will sit there and try to come on a number of times (compressor will also kick back on with it), but usually, I have to turn the ac off for a few seconds, then back on. After that, it will sometimes run just fine for a while, and sometimes shut right back down. Hitting hard bounces/potholes don't seem to affect it.

So far, I've checked all the grounds (battery to motor and to core support, behind #6 valve cover, under dash to the right of the steering column), gave the blower motor a new ground, put the blower on a relay, replaced the ac fuse, tried running it on High with the resistor (behind the glovebox) unplugged, tried running it at different fan speeds, tried running it on max-ac/ac/vent/heat/defrost, reseated the plugs, and sprayed the buttons and switches down with electronic cleaner. Headlights don't dim when the ac system shuts off or comes on, and the alternator is pushing out 13.5 volts (think that was with headlights on, maybe the ac as well). Still having the same issue though, and it has been getting worse.

I did notice today that, when the ac was on, I tried to put the window up (factory electric), it moved up a little ways, then it died as did the ac system. Window motor didn't get any power until I pressed the off button on the ac panel. Played with the window a little after the ac system came back with no breaks in power. Coincidence or symptom, I'm not sure.

Yall have an idea of what else I need to check?

 

 

I have the 92 wiring diagrams and the common things between the Window motors and the A/C fan is the ignition switch and the bulkhead connector.

 

Check the fuseable links under the hood. The '93 I had years ago did the same thing but not intermittently. Both the A/C and the window motors quit. Fuseable link under the hood had burnt into. Good luck.

 

I am having the same problem with my 93. Doing some research I believe it's the resistor that's going out. It's behind the glove box held by two screws. My question is....Is it 2 screws or is it a bolt and nut? I try loosening it and it just spins. Thanks

 

Sometimes a sheet metal screw into plastic or sheetmetal will lose the threads up near the head. Try putting a flat screwdriver under the resistor or screw head to gently pry it up while unscrewing it to see if it will screw out. I really doubt they have nuts on the back.

Edwin