90 Grey button no Max button Climate Control bad?

[azmikep]

Hello Guys.
Thanks in advance for anyone taking time out if there day to try to help me out.
I was driving down the road and all of a sudden AC climate control module display went blank. Same time AC including blower motor stopped.
Now I have nothing from AC climate controls. Nothing on display and noting actually happening.
I have the Grey Button AC climate control module without the “max
Button” in the picture below.
When I got the Truck there was a Black Button without “max button” AC climate control module floating around the truck. That made me nervous, but to my surprise I installed and had AC charged and it worked just fine. That was about 5000 miles ago.
As a side note I have; and was working fine, 100% new AC system. Condenser, evaporator, orrifice, Freon, dye, compressor, both lines etc. Also, the radio head unit needs to be tapped on once in a blue moon. Don’t think the two are related. Just wanted to mention it because if it’s close proximity to climate controls along trucks wiring harness.
I barely understand auto electric; so please don’t be afraid to dumb it down for me.
I own a multimeter, I understand positive and negative and simple circuits. Resistance, Relays, and really anything above continuity do not really understand. (Have a feeling I may be learning lol).
I’m willing to do whatever it takes to fix this. I’ve only found one source for climate control modules rebuilt. Summit has the Dorman 599-012 which from reading on here doesn’t work display flashes and quits.
I’m in Florida now.
Would LOVE some advice on:
1. A place that will repair my “No max button” AC control module.

2. A way to get AC working by jumping something off at female Plug that goes on AC Control Module (see pic?). I figured I can send 12V to blower motor easy with a jumper.


3. A factory or aftermarket part number for a Grey Button, No “MAX” button AC Control Module.

4. Any advice on testing anyway for a novice that can help me determine it is 100% my issue? (Display doesn’t light up and it was so I think it’s right part to get)

 

[1998_K1500_Sub]

Well, let's start off simple...

Did you check that 25amp "AC HTR" fuse which is shown in the schematic you posted?

Other than that, I'll ask you to please provide a little more detail:

What year is your vehicle?

Did it come with AC or did you try to retrofit the OEM parts onto a non-AC vehicle? (I think I know the answer but I'm asking).

You said "When I got the Truck there was a Black Button without 'max button' AC climate control module floating around the truck. That made me nervous". Can you explain this again with a little more detail, because I'm confused.

Not to complain, but can you post a better picture of the schematic? When I zoom in, it's fuzzy (for me, anyway).

I'll commend you on your posting, as you've done some homework and posted what you found... which helps us help you(!).

 

[someotherguy]

These controls don't often go bad. I think a number of them have been assumed to be bad because of external failures. There's a power connection in the harness near the passenger side toeboard (or maybe behind the dash) area that can burn up and cause a blank display/dead controls. It's a 2 or 3 wire connector - sorry I don't have more specifics, it's been forever since I messed with one, just suffice it to say I believe the 88-94 A/C controls are a lot more sturdy than most give them credit for. the 95-up.. that's another story; those are weak junk.

Richard

 

[1998_K1500_Sub]

There's a power connection in the harness near the passenger side toeboard (or maybe behind the dash) area that can burn up and cause a blank display/dead controls. It's a 2 or 3 wire connector -

Might that be connector C235 mentioned in the OP’s attached images?

 

[someotherguy]

Might that be connector C235 mentioned in the OP’s attached images?

Beats me. If you mean in his first wiring pic, that's for a non-A/C truck.

Richard

 

[1998_K1500_Sub]

Beats me. If you mean in his first wiring pic, that's for a non-A/C truck.

I saw that. I figger’d the connector was indicated as being unused in non-A/C truck in that drawing, but still present (and used?) in the AC trucks.

One of the OP’s other images makes reference to that connector, dunno if you saw it. Hence, my thoughts.

Regardless you’ve given OP something to chew on.

 

[azmikep]

ok guys thank you all I'm off work now and going to locate the fuse. can't believe I forgot to say its a 1990 GMC Sierra c1500 originally a 305tbi swapped to 350 tbi only difference was injector size in throttle body. I'm trying to relocate schematic to get better pic was on a google search

 

[PlayingWithTBI]

I'm trying to relocate schematic to get better pic was on a google search

You should be able to find what you need here.

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

 

[LTC_]

Mine went out shortly after getting my truck. Replaced the unit with a junk yard one and all is good again.

Do you still have the black module that came with your truck? You can always try plugging it in.

 

[Donald Mitchell]

I'm suspicious with everything quitting at once. Check wiring and voltages before you buy anything and I do hope it's easy to find.