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    Confirm my heater valve problem

    I picked up a 1990 535i/5 about 3 weeks ago now, and I'm 99% sure the heater valve is faulty. It was stuck on full heat out of both sides when I got the car, fan controls work as they should. It started to occasionally work and I could have the AC on, but hot air would still come out of the front foot vents. Does all this sound like the two electronic heater valves under the hood? I just want confirmation before I drop 150 on the new part.
    The first car I ever rode in was an e30

    Originally posted by Cabriolet
    Wish you the best and hope you don't remember anything after 10pm.



    1992 Mauritiusblau Vert
    2011 Alpinweiss 335is coupe

    2002 540i/6 Black/Black
    2003 GSX-R 750 (RIP)

    #2
    Sounds like it, im bypassing mine till the temps cool off and replacing my heater valve with a new one. The seals in them fail and sometimes the motors too.

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      #3
      Oh, I actually have an update on this. I replaced the valve, it didn't fix anything. Took it to a shop because I didn't have time to deal with it and it turns out the computer that controls the heater valves (because of the over complicated design with the interior temperature sensor and brain to pulse the valves for partial heat) is faulty. Since that $800 part is NLA I had them override the system with a single switch to apply constant power for cold and ground for hot. The rest of the controls actually work as they should now on the top vents and such.
      The first car I ever rode in was an e30

      Originally posted by Cabriolet
      Wish you the best and hope you don't remember anything after 10pm.



      1992 Mauritiusblau Vert
      2011 Alpinweiss 335is coupe

      2002 540i/6 Black/Black
      2003 GSX-R 750 (RIP)

      Comment


        #4
        Originally posted by Vivek View Post
        Oh, I actually have an update on this. I replaced the valve, it didn't fix anything. Took it to a shop because I didn't have time to deal with it and it turns out the computer that controls the heater valves (because of the over complicated design with the interior temperature sensor and brain to pulse the valves for partial heat) is faulty. Since that $800 part is NLA I had them override the system with a single switch to apply constant power for cold and ground for hot. The rest of the controls actually work as they should now on the top vents and such.
        This is epic. I am pretty sure the car I picked up has this problem. AC blows cold as ice but I get no heat. Is there something on the web explaining that needs to be done to get it switched like that?
        Si vis pacem, para bellum.

        New Hawtness: 1995 540i/6 Claptrap
        Defunct too: Cirrusblau m30 Project
        Defunct (sold): Alta Vista

        79 Bronco SHTF Build

        Comment


          #5
          Originally posted by marshallnoise View Post
          This is epic. I am pretty sure the car I picked up has this problem. AC blows cold as ice but I get no heat. Is there something on the web explaining that needs to be done to get it switched like that?
          Sorry I haven't been active in a while. Check this page out http://www.bmwe34.net/E34main/Trouble/Heating.htm to get familiar with the system. The valves have 3 wires to them: power, ground, and one more that I think its from the control unit. All you need to know is that 12v power closes the valves (cold) and ground opens them (hot). The system is designed to pulse them open and closed to maintain the desired temperature...
          The first car I ever rode in was an e30

          Originally posted by Cabriolet
          Wish you the best and hope you don't remember anything after 10pm.



          1992 Mauritiusblau Vert
          2011 Alpinweiss 335is coupe

          2002 540i/6 Black/Black
          2003 GSX-R 750 (RIP)

          Comment


            #6
            Originally posted by Vivek View Post
            Sorry I haven't been active in a while. Check this page out http://www.bmwe34.net/E34main/Trouble/Heating.htm to get familiar with the system. The valves have 3 wires to them: power, ground, and one more that I think its from the control unit. All you need to know is that 12v power closes the valves (cold) and ground opens them (hot). The system is designed to pulse them open and closed to maintain the desired temperature...
            Thanks Vivek. I appreciate the bump. Brings the thread full circle.
            Si vis pacem, para bellum.

            New Hawtness: 1995 540i/6 Claptrap
            Defunct too: Cirrusblau m30 Project
            Defunct (sold): Alta Vista

            79 Bronco SHTF Build

            Comment

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