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::confused:: Unfathomable AC Problem

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    #1

    ::confused:: Unfathomable AC Problem

    I just recently purchased my FIRST E30. A 1991 318i sedan from a local fella.
    One of the main selling points for the car was that it had a freshly redone AC system which blows ice cold air (and it truly does), which is an absolute necessity around here during the hot muggy summer months.

    The problem I am having is with the AC controls.

    Starting point of the AC system before the car is turned on:



    1. Blower speed is at "0" (blower motor OFF).
    2. Temperature is at the coldest setting.
    3. "AC" button (the one that engages the compressor) is OFF.
    4. "Re-circulation" button is ON.
    5. Middle slider (one that blows air on your face) is all the way to the right (OPEN). The other two sliders are all the way to the left (CLOSED).

    At this point, when I turn on the car what SHOULD happen, according to my years of experience in driving regular automobiles with perfectly working AC's, is.... nothing.

    Because the blower motor speed is set to "0". No air should be pumped into the cabin. Furthermore, since the re-circulation button is ON, even if I drive the car, there should be no residual air coming into the cabin since all the flaps and whatnot should be closed, securing the cabin in terms of outside air coming into the cabin through the vents.

    HOWEVER!

    What actually happens when I turn my car on is that the blower motor starts spinning and blows air into the cabin.

    VIDEO (Please watch with earphones/headphones with volume turned up so you can hear the minute noises that I am referring to.


    0:11 - ignition turned to "accessory" (engine not ON); blower motor kicks on and air starts to blow into the cabin
    0:23 - blower speed changed to "1"; notice the slight pitch change in the blower motor indicating slightly higher RPM
    0:25 - blower speed changed to "0"; pitch changes again to lower pitch but still does not turn off and blows air
    0:28 - blower speed changed to "1"; pitch changes again to higher pitch
    0:31 - blower speed changed to "0"; pitch changes again to lower pitch but still does not turn off and blows air
    0:36 - close-up video of air vents to let you hear the air coming out
    0:37 - blower speed changed to "1"; pitch changes again to higher pitch
    0:40 - blower speed changed to "0"; pitch changes again to lower pitch but still does not turn off and blows air
    0:43 - blower speed changed to "1"; pitch changes again to higher pitch
    0:46 - blower speed changed to "0"; pitch changes again to lower pitch but still does not turn off and blows air
    0:50 - re-circulation turned OFF; blower motor stops spinning and stops blowing air into the cabin; you can hear the servo motors engaging the flaps to open them but the motor does not stop and you can hear the motor continue to whir/buzz in the background
    1:07 - re-circulation turned ON; blower motor comes back on and blows air into the cabin
    1:10 - close-up video of air vents to let you hear the air coming out again
    1:13 - re-circulation turned OFF; whirring/buzzing noise from re-circulation flap motor is back and can be heard
    1:24 - re-circulation turned ON; blower motor comes back on and blows air into the cabin
    1:30 - "AC" button turned ON; activates the electric fan in the engine bay
    1:38 - "AC" button turned OFF; electric fan shuts off
    1:45 - engine started
    1:54 - "AC" button turned ON; compressor is engaged and cold air starts to blow into the cabin (keep in mind the blower speed is still set at "0" at this point. There should be no air coming into the cabin even if the "AC" button is turned ON)
    2:02 - "AC" button turned OFF; compressor is disengaged and regular cabin air gets re-circulated by the blower motor (which again should not be on since the blower speed is still set at "0")
    2:06 - "AC" button turned ON; compressor is engaged and cold air starts to blow into the cabin
    2:12 - "AC" button turned OFF; compressor is disengaged and regular cabin air gets re-circulated by the blower motor
    2:14 - re-circulation turned OFF; whirring/buzzing noise from re-circulation flap motor is back and can be heard
    2:24 - "AC" button turned ON; whirring/buzzing noise from re-circulation flap motor is back and can be heard while the compressor is engaged and cold air starts to blow into the cabin

    SO!

    Basically, whenever I have the re-circulation ON, the blower motor turns on even if the blower setting is set to "0". When I turn the re-circulation OFF, then the whirring/buzzing noise comes on from the flap servo motor.

    So it comes down to, would I rather have the air always blowing in my face (blower motor ON) or listen to that annoying whirring noise.

    Anyone have ANY idea what this is being caused by?
    Tags: None
    #2
    i dont know what the problem is, but i can tell you that my car does the exact same thing, minus the cold air, lol.

    318is, m50tu g240 s3.46

    Comment

      #3
      Are you positive the blower speed knob hasn't skipped and is reading inaccurately? Maybe an indicated "0" is an actual "1?" I don't know if you use all four speeds, but obviously if it only goes to 3 that might be the case.
      Interested in vintage cars? Ever thought about racing one? Info, photos, videos, and more can be found at www.michaelsvintageracing.com!

      Elva Courier build thread here!

      Comment

        #4
        When the key is in the ON (RUN) position and any of the following occurs the blower will run:
        1) AC button is on (depressed)
        2) Recirc button is on (depressed)
        3) Fan speed switch is in position 1, 2, 3 or 4

        Why this occurs with the key in the ACC position would indicate some mis-wiring.

        With the motor running and the AC button on the blower is supposed to run even if the fan switch is on 0 - this keeps the evaporator from icing up.

        The whir/buzz most likely indicates a problem with 1 or both recirc door motors.

        Comment

          #5
          Originally posted by pmat View Post
          i dont know what the problem is, but i can tell you that my car does the exact same thing, minus the cold air, lol.
          That gives me some hope that mine isn't going crazy! Thanks for the comment.

          Originally posted by ELVA164 View Post
          Are you positive the blower speed knob hasn't skipped and is reading inaccurately? Maybe an indicated "0" is an actual "1?" I don't know if you use all four speeds, but obviously if it only goes to 3 that might be the case.
          Blower speed knob is not broken or skipping. 1-2-3-4 all work in increasing intensity. But 0 is just as strong as 1, albeit a little tiny bit less, as you can hear from the video.

          Originally posted by vpilarrt View Post
          When the key is in the ON (RUN) position and any of the following occurs the blower will run:
          1) AC button is on (depressed)
          2) Recirc button is on (depressed)
          3) Fan speed switch is in position 1, 2, 3 or 4
          Wait... do you are saying if 1,2, or 3 is true, the blower motor will run when the car is on?
          This is for ALL E30s?

          So then nothing is wrong with mine?

          Originally posted by vpilarrt View Post
          With the motor running and the AC button on the blower is supposed to run even if the fan switch is on 0 - this keeps the evaporator from icing up.
          I did not know that. That may explain that portion of the mystery..

          Originally posted by vpilarrt View Post
          The whir/buzz most likely indicates a problem with 1 or both recirc door motors..
          Thank you for that. Any DIY write ups on how to fix this issue? That noise is driving me nuts!

          Comment

            #6
            Wait... do you are saying if 1,2, or 3 is true, the blower motor will run when the car is on?
            This is for ALL E30s?
            As far as I know its for all E30s, but its definitely true for your '91.

            Comment

              #7
              My '91 318is does the same thing, if you have it on recirculate it will blow very lightly. It is called the recirculate button, not just cut off outside airflow button.

              You should be rejoicing you have ice cold AC bud.
              Different strokes for different folks.

              Comment

                #8
                ^ first things first... DAMN THAT IS FRESH! Digging your ride.

                So let me get this straight.
                Yall are telling me air will always be blowing?
                Let me paint you a scenario for you. I am driving on the hwy going 55 mph like a good law-abiding citizen that I am. I have my recirc button dis-engaged (OFF) so I am getting all the nasty smell outside coming into my cabin from the nearby cow pastures since the flaps aren't closed. I press the re-circ button and the flaps close and the smell does not come into the cabin anymore. But the blower motor kicks on and starts recirculating air through the airvents. My eyes dry up. I turn off the re-circ button again and simply due to the car moving at 55 mph, outside air gets pushed through the AC system into my cabin. which dries my eyes and stinks up the cabin cause of all the poop and stuff from the nearby cow pastures.

                damn it... so then my only route to sanity is to fix whatever is not holding up the servo motor after the flaps open.
                I hear the motor working and the flaps opening for the first 1-2 sec and then after the flaps open, the motor just keeps spinning. it's like its missing a stop or something that prevents it from continuing to spin.

                I did search on here but there were only 1 or 2 threads about and no real solution.
                Anyone?
                Last edited by kkamakasi; 03-13-2013, 03:13 PM.

                Comment

                  #9
                  The motor is not missing a stop, it just stalls when the flap reaches full travel and holds the flap in that position. If the motor shaft-to-door connection is loose or broken the motor will continue to spin. That's probably what you're hearing. The system is designed to normally be in the fresh air mode (recirc off = not depressed). Sounds like you only solution is to get some Visine and move away from all the cow poop.

                  Comment

                    #10
                    Originally posted by vpilarrt View Post
                    The motor is not missing a stop, it just stalls when the flap reaches full travel and holds the flap in that position. If the motor shaft-to-door connection is loose or broken the motor will continue to spin. That's probably what you're hearing. The system is designed to normally be in the fresh air mode (recirc off = not depressed). Sounds like you only solution is to get some Visine and move away from all the cow poop.
                    So no way to replace this motor shaft-to-door connection?

                    and the cow poop was just an example lol

                    Comment

                      #11
                      Yes, you hit the recirc button the blower will turn on.

                      Either put it down to your feet or simply slide the sliders (feet, dash vent, top vent) to the closed position.
                      -Build http://www.r3vlimited.com/board/showthread.php?t=295277

                      Comment

                        #12
                        Sure there's a way replace it. Dig around under the dash until you find out what's broken/loose/worn and look for another part at the junkyard, post a WTB here or look at the car parts and parting ads here.

                        Comment

                          #13
                          Originally posted by vpilarrt View Post
                          Sure there's a way replace it. Dig around under the dash until you find out what's broken/loose/worn and look for another part at the junkyard, post a WTB here or look at the car parts and parting ads here.
                          I was look for something more in detail...
                          But i gotcha. ;)

                          Comment

                            #14
                            Hope I didn't come across as a smart*ss its just that its hard to tell you how to fix it if we don't know specifically what's broke.

                            Comment

                              #15
                              In the below picture, which flap is the flap that opens and closes when I press the "recirculate" button?

                              Comment

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