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Thread: Heat/AC panel change out

  1. #1
    Join Date
    Mar 2006
    Location
    Harrah, Oklahoma
    Posts
    89

    Unhappy Heat/AC panel change out

    I know this is not diesel engine related but don't know where else to turn. My blower control has decided to work only on the lowest setting and the highest. Position 2 and 3 provide no joy. So I went to the dealer and bought the replacement control panel (blower speed, temp, vent selector) but it has been superseded by an updated design. My old panel was hard wired but the new panel has the famous flexible printed circuit on it. The connection on the right goes to a 10 position plug, which I had to go to a salvage yard to get but now have to connect it to the wires in my truck. I am not particularly wanting to buy a years subscription to an online service just to see the wiring schematic for a 97 or so C2500. Any place where I can find such wiring details online? Without breaking the bank?
    95 GMC C2500, 449,000 miles, 4L80E w/ 4.11, 4 inch exhaust, gauges, OPS relay mod, Cold start & Fast Idle controls, 18-1, PMD cooler, coolant updates, cam gear drive, Chinese HX35W clone., Kennedy Max Effort chip

  2. #2
    Join Date
    Apr 2001
    Location
    CA
    Posts
    13,573

    Arrow

    The problem you describe is usually caused by either a burned connector at the control head, resistor module or blower motor, or resistor module failure (most likely suspect). These are easy and inexpensive to diagnose and repair. The 97 models have a solid-state resistor, which can be difficult to identify as failed by visual inspection, but can be pinned out and checked for continuity. The PCB is relatively easy to read and ID the circuits, although they are inexpensive and generally just replaced of connector issues aren't evident.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  3. #3
    Join Date
    Mar 2000
    Location
    South Central Pennsylvania, USA
    Posts
    2,697

    Default

    My a/c panel has been getting glitchy in both the K2500 and Yukon. I was wondering how much of a pain it would be to correct.

    The analog controls in the Saab, Toyota, and Mustang are just as effective as the digital controls in the GMs and a whole lot easier to deal with any issues.
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  4. #4
    Join Date
    Mar 2006
    Location
    Harrah, Oklahoma
    Posts
    89

    Default

    If I hold my mouth just right, position the fan speed in the 3rd position, wiggle it just a little and hold it just right I can get the third speed, for a while. Therefore I conclude the fan speed switch is defective. I have had a few minor problems with the controls, like the A/C sometimes does not choose to come on when the switch is depressed so I chose to replace the whole panel. But finding the wiring diagram for the panel is troublesome.
    95 GMC C2500, 449,000 miles, 4L80E w/ 4.11, 4 inch exhaust, gauges, OPS relay mod, Cold start & Fast Idle controls, 18-1, PMD cooler, coolant updates, cam gear drive, Chinese HX35W clone., Kennedy Max Effort chip

  5. #5
    Join Date
    Mar 2006
    Location
    Harrah, Oklahoma
    Posts
    89

    Default

    Part of the problem is that my old control is hard wired like the 94 but the replacement has the PCB, the numbers of wires leaving the control is not the same and the wires are not the same color. Arrrggghhhh. I have checked Chilton's and like always, the information doesn't agree with either the original wiring or the new panel.
    95 GMC C2500, 449,000 miles, 4L80E w/ 4.11, 4 inch exhaust, gauges, OPS relay mod, Cold start & Fast Idle controls, 18-1, PMD cooler, coolant updates, cam gear drive, Chinese HX35W clone., Kennedy Max Effort chip

  6. #6
    Join Date
    Mar 2006
    Location
    Harrah, Oklahoma
    Posts
    89

    Default

    OK problem solved, returning part to local dealer, ordered replacement part online that comes with pigtails to directly hook into my truck. And a better price.
    95 GMC C2500, 449,000 miles, 4L80E w/ 4.11, 4 inch exhaust, gauges, OPS relay mod, Cold start & Fast Idle controls, 18-1, PMD cooler, coolant updates, cam gear drive, Chinese HX35W clone., Kennedy Max Effort chip

  7. #7
    Join Date
    Dec 2005
    Location
    Klamath falls/keno Oregon
    Posts
    466

    Default

    I bought mine on e-bay..they will sell u what you need
    06 1ton 4X4 duramax/6speed ext.cab WT
    Hummer wheels :^)
    dual lift pump
    Banks air intake

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