90 Grey button no Max button Climate Control bad?

[DerekTheGreat]

Came to say what others said about the wiring, check that first. More specifically, there is a harness just under the glove box that burns up and can cause funkiness and perhaps a fire in the worst case scenario. Pull the glove box lid and then the black bin with the RPO sticker on it and that harness will practically be staring you in the eye. I think only the early trucks had it or trucks from 1990-1992. But inspect it for damage/burns and replace/repair as needed. I came across a '92 like that, the HVAC just quit and the display died with it, IIRC. I spliced in a new connector and all was well again.

 

[azmikep]

Ok. I did check the fuse and I used a test light that hooks up to positive and negative of my battery. Test light has two leds in its handle. Red shows positive, green shows ground.
Just as plug ac module goes in sit left to right (key on) below pic you can see
+ for positve
• for nothing
- for negative

 

[azmikep]

I also went under the hood and used test light to probe the fuseable links (about 5) coming off the positve buss bar (maybe) on both sides of the fuseable links. All had power before and after links.

 

[azmikep]

A little more info on the truck….
Came with factory AC
Came with 305
Swapped in a rebuilt 350 longblock
Used factory throttlebody and everything else because it all fit and would bolt up.
Installed 100% new everything for AC system months ago and was working fine
Compressor, orifice, evaporator, high-pressure hose, low pressure hose condenser.
I had my truck stuffed in my garage. I can now get to behind the glovebox plug. I’ll let you guys know what I find.
And thank you all. First timer on a forum. You guys are a wealth of knowledge. I know just enough to be dangerous. Lol.
Pics of my baby below.
1990 GMC Sierra 2wd Shortbed

 

[DerekTheGreat]

Nice lil regular cab shortbox you've got there.

 

[azmikep]

Thanks Sir. TONS of sentimental value to me. Was my best friends and roommate at the times truck that passed in an electrocution accident in August 1995. My 18ty Birthday was his funeral. Sat since then. Almost 30 years to the day after his accident; I bought it off his Mom. That was Sept 2021. About $17k later; I’ve got a zero miles new to me truck.
This truck will get passed on to my kids. His Brother and I are best friends to this day.

 

[DerekTheGreat]

Wow, that's awful. At least the truck lives on, glad his mom kept it. I always think of my dad when I drive his old Firebird.

 

[1998_K1500_Sub]

I can now get to behind the glovebox plug. I’ll let you guys know what I find.

Looking forward to hearing about it, thanks for keeping us updated

 

[azmikep]

Came to say what others said about the wiring, check that first. More specifically, there is a harness just under the glove box that burns up and can cause funkiness and perhaps a fire in the worst case scenario. Pull the glove box lid and then the black bin with the RPO sticker on it and that harness will practically be staring you in the eye. I think only the early trucks had it or trucks from 1990-1992. But inspect it for damage/burns and replace/repair as needed. I came across a '92 like that, the HVAC just quit and the display died with it, IIRC. I spliced in a new connector and all was well again.

You guys are my heroes!!! Look at that butcher job in there. Melted. I added a fuse properly until I can get a circuit breaker in there

 

[azmikep]

It was the electrical connector behind RPO sticker under my glove box liner!
Thank you all!
I’ve cold AC again. It even solved my radio glitch and a dash “brake” light.

Thank you guys so much for helping me out. I genuinely appreciate it