1987 Bmw 325i Auxiliary Fan Wiring to Temp Switch

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    • Phallus

    TSchager

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    I have a 1992 325ic. The air conditioning works fine but when I go it on, the aux cooling fan, which should surface at low speed, does not operate. The fan also does not arouse when the engine gets white-hot. The resistor battalion was changed in 2022 and the replacement (Magna) looks to be in good mould with no burning of the wires or the housing.

    Here's what I've tested:
    1) When the ignition is turned on and when the AC is turned on, I disconnect the 3 prong plug from the temp sensor located on the radiator. Bridging across the black/brown and ill/black causes the winnow to run at high velocity. Bridging across the black and super acid/shameful does not turn the fan along at low-pitched belt along.
    2) Swapping the low and high speed winnow relays (K1 and K6) does not change anything.
    3) Fuses 19 and 3 are screening 12 volts.
    4) Fuse 18 does non seem to show electromotive force. This seems unmatched.
    5) For grins, I ran jumpers directly from the stamp battery (positive and negative) to the resistance pack leads ahead and behind the cooling system fan. This is a black wire. there are 2 wires running to the buff, a red and a brunet. If I connect the jumper to the resistor connector between it and the fan, IT comes on at alto speed (12 volts). If I join the jumper so potential difference needs to fling through the resistor, cipher. Atomic number 102 voltage and the fan does non fare on.

    I've done what I desired non to do until knowing what is wrong by ordering a new-sprung resistor ingroup and a new thermo switch for the radiator. It seems the testing I've done would have bypassed the thermo interchange A part of the examination but this is acquiring frustrating and maybe throwing parts at the problem will eventually clear the issue.

    Does anyone have an idea of what may be immoral? I'd really suchlike to turn back on my Atomic number 89 with the car continual and have the aux winnow turn on at debased sped. Any assistance would personify greatly comprehended.

  1. You have the etm? 6454 is the wiring diagram, analyzing the circuit hopefully gets you there, simply you'll probably want to flavor over the whole a/c system opening at 6410.

    http://wedophones.com/Manuals/BMW/1992 BMW 325i Convertible Electrical Troubleshooting Extremity.pdf

    Not an result I've had so Don't know if I can put up much insight. If the room the low speed workings is the resistor serves to reduce the electric potential so the lesser voltage is the fan's low or normal speed and the resistance's out, then I guess IT would be replacing the resistor.

    • Member

    TSchager

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    "You have the etm? 6454 is the wiring diagram, analyzing the circuit hopefully gets you there, simply you'll probably want to look over the whole a/c system starting at 6410."

    etm? Wow, thanks for this link. I was looking for the wiring diagrams to understand the flux and parts involved to trace and diagnose. Thank you!

    • Member

    TSchager

    Post Count: 7
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    ETM. Got it. Sorry to be so dense. PDF saved and foliate 95 printed. Time to do some checking. I sure hope the wiring harness didn't smoke when the original rooter resistor fried when the prior owner had it replaced but will check C113 and the wiring. Thanks again.
    • Extremity

    TSchager

    Post Count: 7
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    MGarrison,

    Thanks a lot for the link and the information. I did the following testing supported on the advice and also supported on the schematic:
    1) removed relay K1 and jumpered across terminals 30 and 87. Tested the impedance of the resistor without the key on. Information technology showed 6 ohms. Turned the key and AC turn on and got 11 volts to one side of the resistor. The other side showed cardinal volts.

    2) Put K1 back in the relay position and repeated the test. Zero voltage when the key turned on and Alternating current switch also on.

    3) repeated the jumper try where a positive and ground wire was connected directly to the battery. A jumper was also placed between the black and green black wire of the connector to the temp sensor on the radiator to remove the sensor/switch from testing. The fan runs at high up speed with the jumper along the lover side of the resistor and nothing when the jump shot is attached to the low speed side of the resistor.

    I am now assuming the system has a bad relay in position K1 and besides a bad resistor. Do these assumptions look correct? I judge it's achievable thither are issues with the connector at C113 but I have no idea where the connector is located.

    Thanks again for your help.

    Terry

  2. Sounds logical to me, with the caveat I'm no expert on electrical. The ETM has part location and views, unfortunately sometimes the pictures aren't so great - see power on 9000-4 (p.140) & figure 5 on 7000-1 (p.105), that should get you to the connector to watch from there. Presumably you adage the listing of the wiring color abbreviations happening 3 (p.5), although the abbreviations are besides pretty straightforward.
    • Member

    TSchager

    Post Count: 7
    Likes Standard:1
    Thanks for the tip on the forefinger. I did see the colorise abbreviations. This document is priceless. Thanks again for sending the link.
  3. If you coif your own maintenance, the E30 Bentley manual is meriting having - it's non perfect, some how-to's are lost or glommed-over in around instances, but whatever it doesn't deal can most-likely comprise found searching the 'sack up -

    http://www.bentleypublishers.com/bm...bmw-3-series-e30-1984-1990-repair-manual.html

    I trust your a/c fix industrial plant forbidden to exist as retarded atomic number 3 the relay & resistor!

    • Penis

    TSchager

    Post Count out: 7
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    Yup. Got 2 of them. Incomparable in the car and the other in my office for reference. The Bentley doesn't get more or less the detail the ETM provides. Both are great resources though. Thanks again.
  4. Yeah, Bentley has some wiring diagrams, simply non that one; got me curious to look, Bentley does have a chart of splice and connector locations, merely none pics like the ETM. I Don't know who hosts that wedophones site, but it's handy, has been there for a age now & thankfully still is. Glad to be of any helper!
    • Member

    TSchager

    Post Count: 7
    Likes Received:1
    Good, the plot thickens. Information technology looks like the auto has issues with grounds at the fuse/electrical relay panel (Relay K1). I've changed proscribed the resistor (it was bad) and the temporary worker sensor (low stop number trigger was bad). Turns out thither's a link happening Bimmerforms that talks about this job.

    The link is: https://WWW.bimmerforums.com/forum/...ighlight=supporte with AC auxilliary Fan K1 relay. My pin 86 on the K1 relay was not going to ground. I created a jumper to K6 Pin 85 and fanned the leads out like it aforementioned in the blog.

    My car had exactly the same problem with pin 86 on K1, where the ground got disconnected somehow all over time. Low speed operation connected both temporary worker and AC military operation now bring. Steep speed works overly.

    In the end, the fix involved replacing the temp switch happening the radiator, the resistance and the jumper. I suspect both the switch and resistance were corked due to a bad/failing ground on rowlock 86 that caused them to conk out but we'll never know. Bottom line is that it is fixed thanks to your help and that of the link ended happening BimmerForums.

    This ought to be a sticky on the CCA website and meeting place because others have and will run into this. Debugging is a lot of work.

    Thanks over again!

    Terry Schager

  5. Kudos happening working it through and through & getting it squared - not easy w/ septuple issues ilk that!

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1987 Bmw 325i Auxiliary Fan Wiring to Temp Switch

Source: https://www.bmwcca.org/forum/index.php?threads/aux-cooling-fan-issues.24251/

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