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[Solved] BMW E46 - The blower fan does not work when the engine is started

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  • Level 8  
    Good morning,
    The problem concerns BMW E46 Sedan, 320i, 2000.

    After switching the key in the ignition switch to the second position - the blower starts, ignites the control and everything looks OK. The blower operates without interruption and stably, reacting to changes on the air / air conditioning panel.
    After starting the engine, the blower switches off after 3 seconds. Then it turns on for about 1 second, but only if I run anything else that requires voltage, such as lights, turn signals, rear window heating or air conditioning.

    Since the problem appeared:
    - I replaced the air supply panel by connecting another one - no changes
    - I checked all fuses, not only those responsible for the air supply - they are all OK
    - I changed this relay (click) with horn relay - unchanged. The horn works, so I bet that the relay is operational.

    Some people suggest me to replace the hedgehog (blower resistor) - but it is 200 PLN, and the standard symptoms of a fallen hedgehog I found on the internet do not match mine.
    Does anyone have any idea what to check / do, in addition to the possible replacement of a hedgehog?
  • Relpol przekaźniki
  • Helpful post
    Level 43  
    Yes, I suggest replacing the hedgehog.
    The hedgehog comes with control from the panel.

    Measure whether the control voltage comes from the panel and whether there is a mass and power supply and there is no output voltage.
  • Level 8  
    Ok, I will buy a hedgehog today.

    As for the measurements you mentioned, could you tell me how to measure it? On the engine running, with the hedgehog plug?
    I found something that will probably help me: description of the hedgehog pins in E39. I suspect that the E46 will be much the same.

    I'm seriously a beginner :)
  • Helpful post
    Level 43  
    You go to the scrap yard and ask for a hedgehog and you go with a guy and check with you in the car, before you pull the plastic and the plug from yours for a long time did not bother.
  • Helpful post
    VIP. A meritorious for the electrode
    For now, check one more thing, turn on the ignition and blower, write that it works, then turn the ignition switch so that the engine will start for a fraction of a second, but the car will not fire. If the blower stops working, you have the culprit, the ignition switch will be replaced. Symptoms definitely do not indicate damage to the hedgehog.
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  • Level 8  
    I did the test - "unfortunately" the blower still worked, link to the video below. The first time the engine started - I showed the way when the blower behaves when switching on, for example, heating the rear window.
    The trick you offered in 47 seconds.
  • Level 8  
    I had a regenerated alternator in the autumn, it remains 14-14.1 V (when starting the next voltage receivers visible momentary drops not lower than 13.5 V, but quickly return to 14 - it's probably normal).
  • Level 43  
    Yes, it also happens to me, I sit down after the load at idle and returns.
  • Level 43  
    It was for me whether it does not overload, on the film after the start-up as the altek starts the fan, it increases the speed and goes out ... but when it is 14V, it is not ...
  • Level 8  
    I checked this loading once again and the values are theoretically OK, but I noticed an important thing: I get the impression that the blower stops working when the charging exceeds 13.5V. That's why it works after the ignition is turned on, and after the engine is running for a while - before the charging reaches the value of 14 V.

    The same when driving - turning on, for example, lights causes a temporary decrease in charging, then the blower is activated for this short time.
    Link to the next video showing how it works, that it does not work :) The video shows the charging of the alternator.

    1) So maybe it is an alternator? It's possible that the fault lies on his side despite the fact that the charging is ok?
    2) Is there a chance that the famous "hedgehog" would generate such problems, or are the symptoms not like a hedgehog? :)

    Maybe some other ideas?
  • Level 8  
    Andrew,
    I have measured - the values in the OBC test coincide with those indicated by the meter.

    But I did one more thing - I started everything that I can in the car (long lights, fog, rear window heating, klime, radio, etc.) - the alternator's charge dropped - surprisingly, up to 13 V (the same value in the OBC test and meter) and the blower started to act - which confirms my theory, the blower works when the voltage drops below a certain value.

    Do you bet an alternator? Do you have any idea why the blower works with a higher load (and therefore with less charging voltage), and with stable 14 volts does not want to work?
  • Helpful post
    VIP. A meritorious for the electrode
    However, damage to the hedgehog.
  • Level 8  
    Hedgehog mentioned - it helped.
    It turns out that I have been unaware of the purchase of the car from the purchase of the air supply :)

    Thanks for the help!