W126 heating

Discussion in 'Interior' started by h17n dj, Oct 31, 2011.

  1. h17n dj

    h17n dj Hardcore MB Enthusiast

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    W126 500SEL
    Hello all, i hope that this is in the right section, my apologies if not. My SEL has 2 temperature zones and the drivers side does not seem to be blowing any hot/warm air at all. only cold which is annoying with winter approaching... any clues as to whats wrong with it? a blockage? problem with the heating system? etc........?
    thanks in advance
     
  2. ianrandom

    ianrandom Hardcore MB Enthusiast

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    1986 420SE, 1990 420SEC, 1989 2CV6.
    One of your rubber diaphrams is probably split. In the duovalve ; its inbetween the two firewalls, something like four screws to whip the top off. Then lift out the assembly, there is a little diaphram thing for each side. It cold be split - could be hard to see.

    Otherwise there could be a flap stuck or broekn somewhere. I'd say more likely the duovalve though. Can be got from dealer.
     
  3. OP
    OP
    h17n dj

    h17n dj Hardcore MB Enthusiast

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    ok brilliant.... sorry to sound like a total retard....... but where would i find this?
     
  4. coalville126

    coalville126 Hardcore MB Enthusiast

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    W126 300SE, S210 E55, R107, Subaru Legacy ST
    Drivers side bulkhead (engine compartment), near brake servo.
     
  5. OP
    OP
    h17n dj

    h17n dj Hardcore MB Enthusiast

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    heating is sort of sorted! i went to mb looking for the flap but got confused etc and he said to give the duovalve a tap as one of the motors may not be working and so i did and it started working again :) BUT i got down the road and it stopped. got home and tapped it again and it seems to be working again! im tempted to take the duavalve apart and lubricat the insides or have a little explore?
     
  6. coalville126

    coalville126 Hardcore MB Enthusiast

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    W126 300SE, S210 E55, R107, Subaru Legacy ST
    Why not get a working one off ebay to replace the on your car. Then you could strip, clean and rebuild the original one, assuming no split diaphragms.
     
  7. OP
    OP
    h17n dj

    h17n dj Hardcore MB Enthusiast

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    well just went out for a drive with the fam and the heatings spot on again :) so maybe i got it working again lol! just had a look on ebay and a duo valve is £100 + £7.50 p+p ouchhh! so i'll see how it goes, maybe recondition mine then if i need a new one, have a hunt around
     
  8. coalville126

    coalville126 Hardcore MB Enthusiast

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    W126 300SE, S210 E55, R107, Subaru Legacy ST
    Well done! Now that's what I call an easy fix. You might want to think about flushing your cooling system if your antifreeze is due a change. I learnt that mucky coolant can cause an ageing duovalve and heater pump to play up.
     
  9. OP
    OP
    h17n dj

    h17n dj Hardcore MB Enthusiast

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    indeed. i was pleased lol! i did a thermostat change so i flushed it and cleaned it all out so thats done :) ! put all new antifreeze in and all that. thanks for that though buddy :thumb:
     
  10. johngathercole

    johngathercole New Member

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    Dec 12, 2013
    Car:
    300SE
    I also have heating problems on an 89 300se. The heating won't go off on any position of L and R thermostats. Not a huge problem over winter but I would like to sort. Car was stored unused for 2 years. could this be stuck duo valve too?
     
  11. balge

    balge Hardcore MB Enthusiast

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    Car:
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