Heater issue on '90 FSB

[jramirez35]

Hi y'all,

I know this topic has come up over and over and I read a whole bunch before i posted this. I get lukewarm air when set to heater. I have performed the vacuum leak repairs from some of Steve83's postings and i think i got all of them. I replaced the blower resistor and got all speeds on my blower motor now. I took the plenum door off in back of the glove comp and can see the doors move back and forth (blend door and defrost door). I can physically see the core and can feel some heat off of it. I also felt cold air blowing at the same time and saw that i moved it back to a/c. Moved lever back to heater and the a/c continues to cycle. That is probably the only thing that i could not find a posting on and i am confused. Electrically, the a/c clutch should be off when it is set to heater right? Guy i bought this off of did some rigging to get stuff going and i don't operate that way and want it right but man i don't know what to do with something like this problem. i wanted to pull power from the cycling switch on the accumulator and that should prevent the a/c from engaging but then i haven't really proven a damn thing other than the a/c comes on when the lever is on heater. Any suggestions with this would be appreciated. Also a quick blurb on getting the speed sensor off of the old speedo cable would help too because i have the replacement on hand and the sensor is not part of the new cable. Do i just destroy that retaining clip to get the old one off or is there a trick to it. oh yeah...merry xmas to you all.

 

[jramirez35]

Turn the key to RUN, set the control to MAX, unplug the accumulator switch, & install a 12V test light from either wire to ground. If the light doesn't come on, move it to the other wire. If it's on, set the control to VENT or FLOOR. If it goes off, OR if it didn't come on with either wire, there's power spliced in downstream of the accumulator switch, and it should be visible. If it doesn't go off, set the control to OFF. If it goes off, pull the control head & inspect the switch section for damage/mods. If the light doesn't go off, the control switch is either severely damaged, or bypassed.
The speedo cable is retained in the VSS by a simple hairpin clip. Remove the 11mm (7/16") bolt, pull the VSS out of the t-case, & take a closer look at it. Don't try to remove the hairpin - just push or pull it so the cable can come out. I usually just wiggle the cable (with the VSS still in the t-case) until the cable works itself past the hairpin.

a/c turned out being fine. I can't get the damn thing to reproduce the problem and it is doing fine now in all settings. I will remember this post so that i can troubleshoot it when the problem presents itself again.

Speedo cable came out just the way you said it would with a little bit of convincing. Saw a very nubby little piece of speedo cable on the vss side and figured i had found the culprit. Was wrong of course and i just need a new speedo as well because the needle is well below the speed marks and when i removed the cluster the needle "floated". What i would consider the 0 MPH mark is nowhere near the place that this speedo starts moving from. I do have a generic speedometer that i got at oreillys and it might not be accurate but it is moving the needle. I am curious if there is a way to test out what is inside the transfer case that meshes with the new speedometer gear that i bought. Any ideas Steve83? Once again, thanks again for the quick response.

 

[BroncoJoe19]

The AC will cycle on and off in defrost, and (I Think all settings except Vent). It helps dehumidify the air that way.