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Thread: [E34] Electrical gremlins after some time standing still

  1. #11
    Join Date
    Dec 2003
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    Eastern Tennessee USi
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    14,709

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    Quote Originally Posted by Frank87 View Post
    Before:
    - experimented with a spare IHKA computer( the one with the 3 colored connectors). Same problem.
    - removed the auc sensor and module just in case. Same problem.

    Update to this thread:
    - I have replaced the DME, no change
    - I have replaced the Check Control Module, no change
    - I have replaced the A/C control panel with an identical one, no change
    - I have replaced the 3 buttons defrost/AC/AUC panel, no change

    Problem still remain:
    - cold air doesnt work whether A/C button is on or off. IHKA blows hot only
    - A/C doesnt work, there is no way to get the compressor going. System is leak free and full. All wiring resoldered where needed
    - rear window defroster does not work at all
    - check control on the instrument panel does not work. Bottom bar does not light up and if you shine with a light it says "Check Control, Betriebsanleitung"

    I have a total IHKA rebuilt. Going to swap it in a month or 2. Meanwhile I keep checking the electronics as I work on the car.
    Jump the hot lead to the compressor and watch it work. If not then you can trace it. If it works you can trace it. Not sure if I am missing a whole lot here just reading along.
    95 E34 530I V2.34
    ===========
    Those who make peaceful revolution impossible will make violent revolution inevitable.

    John F. Kennedy

  2. #12
    Join Date
    Dec 2004
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    Quote Originally Posted by 632 Regal View Post
    Jump the hot lead to the compressor and watch it work. If not then you can trace it. If it works you can trace it. Not sure if I am missing a whole lot here just reading along.
    Often the AC compressor will only come on in run IF there is enough gas in the circuit. A good way to check is to get a refill can, tap and gauge pipe, seat the can on a scale, and attach it to the low side (blue) and see if there is any pressure. If you open the tap to introduce fresh refrigerant, be sure to note the mass the can loses, that way you know how much goes in. Sometimes as little as 30g will return the system to pressure enough to allow the low pressure switch to open and the compressor to engage. I have one that needs 50g every few years... I really need to replace the o-rings, oil and gas afresh, but I am not sure I'll ever get the time

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  3. #13
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    Dec 2003
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    Eastern Tennessee USi
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    I have a can of I have not used and sitting on my desk. Debating weather to spend another $32 bux for little cans or get the mega jug for $130. I could have paid for the mega jug already. If it leaks out I have plenty of reserves ready plus maybe make some back filling other peoples stuff. I have all the gauges and stuff to legally do it.
    95 E34 530I V2.34
    ===========
    Those who make peaceful revolution impossible will make violent revolution inevitable.

    John F. Kennedy

  4. #14
    Join Date
    Feb 2015
    Posts
    109

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    I have fixed this problem.

    I have:
    - completely rebuilded an IHKA unit using 2 spares. Out of 3 big IHKA boxes I made 1 very neat, very clean and very good insulated (cut fresh insulation) one;
    - fit and installed the above mentioned IHKA and checked all wirings, connectors and ground points;
    - used a IHKA computer that was a guaranteed run on another E34 with similar IHKA;
    - replaced a blown fuse. The fuse was not related to the IHKA (according to the schematics);

    I now have:
    - working rear window defogger
    - working OBC
    - NOT working mileage/automatic cluster (probably bulbs!)
    - a working A/C;
    - a working "hot" heater in 3 areas;
    - a partially working cold heater (1 area cold only). The middle vent shafts blow cold, the window and foot ventilation keeps blowing warm/hot;

    Anyone have any idea how window/foot area is separated? Could it be that one stepper motor that I put back is bad?

    Either way, I got my A/C back and turning off window/foot area, car blows cold.
    Last edited by Frank87; 06-03-2020 at 04:20 PM.

  5. #15
    Join Date
    May 2004
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    Japan
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    I assume (not sure) that the E32 IHKA is the same function, here are good pics and info what which stepper motor does http://bmwe32.masscom.net/johan/ihka/ihka.html
    pdf Klimaautomatik German language http://www.e38.org/e32/klimaautomatik.pdf

  6. #16
    Join Date
    Feb 2015
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    My final problem, the A/C / cold outside air not blowing at feet and windshield was the passenger water valve not being actuated. I have remade/resoldered the wiring from the harness onto the water valves.

    All works perfect now. I still do not know what the original problem was but since I have also removed wiring to the A/C compressor that should not have been there (completely non BMW wiring bypassing relays) and have used a 100% intact harness from a wrecker, I think whatever problem I had is now gone.

    EVERY electric thing in the whole car now works exactly as it should. No error messages. No error code except for the aux. water pump which I have removed myself.

  7. #17
    Join Date
    Dec 2004
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    Sydney, Australia
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    Great news.

    Have the capacitors in the cluster been replaced? These will need to be done, if they haven't been. Not sure if the shut down the bulbs and doubt it, but if not, it will be a dry joint or a connector. Perhaps try looking- with the cluster apart and plugged in, for 8-12V on the light circuit, and the wiring/connectors leading to the information display PCB.

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    08/88 535i e34 M30+miller MAF, 'stiens, tints & teeth!

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