I too benefited from the direction of reconnecting the negative terminal. I've been dealing with the non-heater issue for months. Checked the fuse several times. This did the trick. Thanks for the post. Now, ... does anyone know of a video online showing how to disconnect and replace the passenger electric window switch?

 

I have a 1990 c1500 and I have tried to unhook the cable like it says on this tread and no go. I have looked at all the fuses they look good I even tried putting another control unit to see if maybe that’s was the problem still nothing any other suggestions that might help me out would be greatly appreciated.

 

My digital air display went out and turned out to be the wire harness behind the ash tray and started melting

 

Brad1964,
I had the same issue as you and I just fixed mine this morning.
My fix - 1st verify that you have power to the controller (it will be the top and bottom on the far right side of the connector, check each one separately, connect your multimeter and turn key to acc. position and you should have voltage around 12v DC) once you verify that you have power to both ports/wires you want to get some electrical contact cleaner and spray out the connector then shake/blow out the connector to remove excess liquid and the remainder will evaporate you should spray off the board in the controller as well just remove the 4 screws holding the case together and gently separate the case, hold the sides of the circuit board and spray down both sides with the contact cleaner and gently blow off and let dry, when everything is dry put back together and hook it back up and try it out, hopefully this will work for you as it did for me, I've also tried the other options in this forum with no luck

 

I also could not be understand the digital controller problem .Some technical problem always increase our frustration. Recently I bought a ac but sometimes ac was not working. Hot temperature always blowing. I think have to change the ac or contact to the ac repair service center. If anyone has any information then suggest to me.

 

I only have power on the top and nothing on the bottom right, why would this be?

 

I had the same issue until I pulled the glove box out and found a plug melted. It was the power wire to the ac. Mine was 1 red wire 1 light green and then a unconnected dark green. Spliced them together and she’s is good..... this is the link that led me to this.

https://www.justanswer.com/chevy/3oy...t-working.html