A/C heat control not working properly

Hello, I'm Danny.

First let's start by checking the fuse. Here is a tutorial show how to check fuses:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

You didn't specify what truck you have like S-series or Full-size as they both are offered the 4.3 L engine. I've attached below the location of the door jamb fuse box. Let us know and we'll go from there. Hope this helps and thanks for using 2CarPros.

If you have the old panel put that back in as the new one has to be programmed to your truck. Check to see if your temperature actuator is getting power or not. See pictures. Also, pull fuse with arrow for sixty seconds with key on. It may reset and give you heat. Finally if actuator is bad do not plug it in until it is installed as it may not work and you will have to do a reset again.

Look at the picture carefully it tells you what box it is in, the one inside the truck.

It is behind a cover to the left of the steering column. If you cannot find it have a local mechanic or auto parts look for it.

Please re read my last reply. It has a cover that has to be taken off or go to a mechanic so they can show you. We have no pictures of this otherwise I would have sent it.

Hopefully you tested the fuse with the key on. Now do as I said in the one reply to pull fuse for htr/ac for 60 seconds with key on then reinstall car can be running if you like it doesn't matter. Then see if you get heat if not then a mechanic has to scan for codes to see if it is the control head. I am assuming you put the old control back in if not the new one will need to be programmed to your vehicle to get power to actuator.

Yes if we had a picture I would have shown it long ago it's a 25 amp fuse.

One wire is getting juice and other is a ground so will not have any juice from your description the actuator is bad

I've sent that info to you previously these pics should show you everything you need if not see a mechanic