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S50 stalls when AC kicks on

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    #1

    S50 stalls when AC kicks on

    My s50 (swapped by PO, not me) would die at idle every time the AC compressor cycled on. I adjusted the idle up to roughly 1,000 RPM with AC off, and now it will idle some of the time at about 600 RPM with the AC compressor going, but still dies a lot.

    I can just keep upping the idle until it idles reliably with the AC, but then the non-AC idle will be pretty ridiculous, something like 1,200 RPM.

    Is it possible that the AC system has too much freon, so it creates too much load on the engine? Is there some other control component the AC system is supposed to have that raises the idle when the compressor is on? Any ideas would be welcome.
    "If the sky were to fall tomorrow, the tall would die first."

    -Dr. Paul Forrester



    Do I LOOK like I need a psychological evaluation???
    Tags: None
    #2
    I would rule out your freon level immediately. Look at your alternator/ voltage regulator. I have seen this happen in offroad racing when turning on HIDs or other large draws. However, if you want to rule out compressor failure like a bad bearing, take your ac belt off and run it with your ac turned on(compressor clutch engages etc.). If it dies, you probably need an alternator. If its normal, get a new compressor.

    Comment

      #3
      Your AC is not telling your ECU that your AC is turning on.

      And don't try to adjust your idle manually... that has to be done with software.

      Comment

        #4
        http://www.r3vlimited.com/board/showthread.php?t=89460

        Originally posted by whysimon
        WTF is hello Kitty (I'm 28 with no kids and I don't have cable)

        Comment

          #5
          I would say high-low switch not adjusting idle. But I'm not sure how BMW does it so I'll go look.


          NM, Fred gave you the info.

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            #6
            I had the same problem with my s50 when my swap was first done.

            Exact symptoms as yours. I would have to keep the revs up slightly while coming to a stop or the car would stall.

            I checked the wiring and sure enough, the A/C signal wire wasn't connected.

            Easy fix and Ahhhh, A/C is so nice.

            Comment

              #7
              FredK - That link was great.

              OK, I found the pigtail and red/black wire from the A/C. What I don't get is how to ID the wire from pin 64 on my 506/gray DME. There's a humongous bundle of wire coming off the DME connector - what's the method or documentation to match wire color to pin 64?
              "If the sky were to fall tomorrow, the tall would die first."

              -Dr. Paul Forrester



              Do I LOOK like I need a psychological evaluation???

              Comment

                #8
                Anyone? Non-electrician here looking for help.
                "If the sky were to fall tomorrow, the tall would die first."

                -Dr. Paul Forrester



                Do I LOOK like I need a psychological evaluation???

                Comment

                  #9
                  The Bentley or ETM (google "BMW ETM") should tell you the wire color, or you can pull the connector off and the pins are labeled pretty clearly.

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