GM Truck Club
Founded in 2004 ~ We're the #1 Chevy Truck & SUV Forum.
Silverado & Sierra | Tahoe & Yukon | Suburban & Yukon XL | SUV & CROSSOVER
Results 1 to 10 of 10
  1. #1

    Default Need help please 1988 chevyc1500 ac/heater unit

    My ac/heater unit is not displaying anything. Everything else on the dash works. I just bought the truck. There is a aftermarket radio in it. Im thinking when they put that in they did something wrong. Anyone know what i should look for.

  2. #2


    What do you mean by not displaying anything? Can you describe it more detailed to help others understand better?

    Also Welcome to the site I hope some one can help you out

    1996 Chevy Tahoe LT 5.7L V8 4X4 205,000+ miles. Built proudly at Janesville Assembly in Janesville, Wisconsin
    Basic mods: Lights all over, bunch of electrical work, and a couple cooling mods.

    Check out my other mods in My Garage:

  3. #3


    Step 1 would be to check all the fuses, even if they dont appear to be related to the system in question, Ive found in the past systems that you would assume to be not related have input or signal wires that allow power up.

    Step 2 would be to open the dash and check for loose plugs, cut wire, or even tape or connectors where a wire might have been repaired. Sometimes novice stereo installers can get a little messy.

    Step 3 would be to use a multi meter to check the system plugs for proper power inputs/outputs.

  4. #4


    Sorry i didnt know i had any replies. I thought i was suppose to get a email. Anywayz the whole control unit does not work. It doesnt have any power. I unplugged it and got a test light and tested the plug. There are 5 wires on the plug and all except the middle wire are showing power. The wire is green. I cant find a wiring diagram for this truck. If you know anything else i would appreciate it. Thank you

  5. #5


    Moilan57 try a Google search using "1988 Chevrolet truck wiring" I found a mess of good wiring diagrams for your truck, unfortunately Im using a Kindle for access so its hard to expend the diagrams and read them.

  6. #6


    If you can't find anything wrong with the wiring, the display driver for the unit, or the logic board may have gone bad. The displays for these trucks were pre LCD/LED and are actualy plasma discharge displays. The driver circuit that excites the display may have given up the ghost. In that case, it's time for a new unit.

    My '89 also has the digital display for the AC/heating/cooling controls. I've noticed that LMC truck sells a replacement, but it is still a spendy little unit.
    Myself, my beautiful wife
    3 - boys
    3 - minivans
    1 - '89 Chevy K2500 Silverado Truck
    1 - 27 foot travel trailer
    Not enough family time!

  7. #7


    Yes i was thinking that also do you know if a good place i can get that ac unit

  8. #8


    I've only seen it in the LMC catalog. I suppose that a U-Pull it yard might have one or two, but you never know if that will work for you until you try to install it.

    Click image for larger version. 

Name:	AC controls.jpg 
Views:	63 
Size:	46.4 KB 
ID:	52514

    LMC wants $599 for the unit. Maybe the wrecking yard will be cheaper.

  9. #9


    Alright i found another problem i took the ac/heater control unit apart. It is the digital one, the third one on the post. Inside the display screen has a burn mark. Do you know what could have blown to cause that. Thank you for your help

  10. #10


    I've never had mine out of the truck, let alone opened up. Maybe someone else will have some experience with repairing one of these.

    Good luck.

Similar Threads

  1. Can anyone help with ac/heater unit not working
    By Moilan57 in forum The Coffee Shop ~ Chit Chat
    Replies: 0
    Last: 05-21-2013, 10:56 PM
  2. 1988 chevrolet c1500 factory stereo and ac unit not working
    By Moilan57 in forum General Chevy & GM Tech Questions
    Replies: 0
    Last: 05-19-2013, 08:37 PM
  3. Replies: 0
    Last: 12-25-2012, 07:10 PM
  4. For Sale Brand New Heater Core 1988-1998 GM 4x4 truck
    By CustomFabMan in forum General Classifieds
    Replies: 0
    Last: 11-29-2012, 11:22 PM
  5. 07 new style Heater/ac control unit
    By stulin in forum General Chevy & GM Tech Questions
    Replies: 3
    Last: 01-28-2010, 03:05 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts