The left side of my HVAC doesn't work but the right side such as my blower motor speed and recirulation button works. Could this be due to the black box on the top of the hvac or something I'm not thinking of? Both sides are given 12V from the same fuse right?


Again as shown below everything on the left side doesn't work. Three of the five lights light up for the blower direction (feet, defrost, in face, etc.) but the temp control doesn't make anything move behind the dash so it is not working.


This black box does what exactly?:



And if I just wanted to remove an HVAC from a donor car and install it in my car do I have to remove the dash to unplug the harness because the harness within the HVAC doesn't just unplug. One has to go up in the dash to remove the harness I think and that is gonna suck.

 

Where in VA are you?

I had this problem with my 1986 GXL.

The harness goes up to the center of the dash... Look between to the two defrost vents in the dash under the front of the windshield... There's a small, flat rectangle. Pry it up CAREFULLY with a screwdriver. (All the plastic up there is 20+ years old. It'll probably break.)

Once that rectangle is removed, there's a nut. I think it's 8 or 10 mm. Remove that nut and another plate that's under it.

The connector goes towards the driver's side of that hole you've opened up. Just jiggle the harness that connects to the back of the HVAC controls (Called the "Logicon")



There may be another way to do this if you have very dexterous arms.

Remove the driver's seat. (Really.. I'm serious.)

Lay down on the floor and rest your head on the pedals. Look up.
Remove all the trim and vent hoses and whatnot.

You'll see that cable. You'll also see another likely culprit, the Heat/Cold air mix motor.
It's held in by three or four screws and has a rod that moves the door to the hot/cold air passages.

In my case, I had gone through three Logicons (Spares... But be careful. New ones are EXPENSIVE!) before I found a spare air mix motor.

 

Logicon, Logicon is the correct name....

Thank you

 

He spelled it correctly..

Anyways the Logicon isn't acuating any of the HVAC controls now. Nothing is working from it and i know it isn't all the motors and the blower motor that is broken. The logicon will light up with orange backlight when the lights are turned on in the car but it won't operate anything now. Anyways I will be going to the salvage yard tomorrow afternoon to see what they want for a used logicon.

 

The FSM has a section called HEATING AND AIR CONDITIONING and it deals with trouble shooting faults in the Logicon and other componets.


The wiring diagrams will point you to the two fuses you might have blown. So will the HEATING AND AIRCONDITIONING SECTION of the FSM.

 

HAILERS thank you for all of your help. You are amazing my friend. Oh and it was the logicon main board that was the culprit as well as a 15A cooling fan fuse. The old logicon would only allow the blower motor and RECIRC button to operate.