Heater controls in a 1990

[scarbrow]

I am getting closed to having my swap done my truck is running but now my heater controls won't work so I have no heat at all. The electronic control pannel doesn't display anything and non of the buttons will do anything.

If i turn on the lights the buttons will light up though so I know I have power at least to the light part of it.

I went to the local salvage yard and picked up two more of the control units to try and neither of them would work either. They would light when the lights were on but wouldn't control anything.

I am starting to wonder if there is one power lead that goes to the unit and a separate one that runs the lighting part of it and maybe the main power got unhooked somewhere along the way when the wiring was being done.

If anyone knows how many power wires go to this please let me know, here is a crude paint picture of what the plug that goes to the back of it looks like. Any help would be great.

[Chevy-Art]

Did you disconnect anything behind the glove compartment? Look where the old ecm was, there is some wiring there that controls the hvac.

[scarbrow]

Any more info on what to look for?

I didn't do the wiring so I have no idea what to look for.

[SpecV44]

my blower wasnt working after removing some wirings, so I was panicing because I wanted my A/C to work. I looked back behind the glovebox and I had unhooked the wire that powered the blower. I guess I knocked it off, simply putting it back on and it worked. Its a 1 or 2 wire plug.

[92 6.0]

I had the gm manual till thursday if I would have now we couldve met up again. But I do have a haynes manual and it shows the diagram for the heat and ac controls if ya need to borrow it or anything. I might be able to just scan it for ya also.

[scarbrow]

I had the gm manual till thursday if I would have now we couldve met up again. But I do have a haynes manual and it shows the diagram for the heat and ac controls if ya need to borrow it or anything. I might be able to just scan it for ya also.

thanks, might have to do that.

I have another question that might help ARE THE HEARTER CONTROLS CONTROLLED OR POWERED BY THE FACTORY 1990 TRUCK COMPUTER?