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W124 aircon - user guide

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by ShivaYash, Dec 25, 2012.

  1. ShivaYash

    ShivaYash Senior Member

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    Your Mercedes:
    W124 1994 E200 estate (M111 engine)
    Hello and merry Christmas to all.

    I wonder if someone can assist. I use the ec button in my car to run the a/c. I know this is ON when the red light is OFF. The a/c is on all the time and I love it. Great for demisting the windscreen in winter. What does the button above this do? I thought it was for demisting but I don't know how to use it. Also. When should the recirculating button be activated? Does these other buttons also work 'backwards'? Ie, to activate, make sure the light is OFF.

    Thanks!
     
  2. huey

    huey Senior Member

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    The button above is a Dehumidifier button, when you use it the air con turns off,
    either can be used with the recirculation button,that is what it says in my handbook:D

    Merry Xmas
     
  3. OP
    ShivaYash

    ShivaYash Senior Member

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    Thanks. Yes on a 175 mile round trip yesterday I used it all the time. But I thought aircon would dehumidify as well? Am I wrong? Which one will use up more fuel?

    How does the car dehumidify? Via the receiver drier unit?
     
  4. television

    television Always remembered RIP

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    Air con dries the air, taking out any humidity, during the winter months it is not working very hard and any extra fuel used is small. you should check that it is working by turning to max cold and the air coming in should be really ice cold.

    The Bosch "tempmatic" that you have is not so user friendly as the fully automatic "Kammerer" or Bosch fully automatic.
     
  5. OP
    ShivaYash

    ShivaYash Senior Member

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    I see. Yes the ac is ice cold. I should know, I just replaced the condenser and receiver drier. So when do you suggest using the dehumidifier system? I have two dials in my car, can this really allow my wife to have the hearing 'up' with my side blowing cold dry air? It's very confusing!
     
  6. mikestrivens

    mikestrivens Senior Member

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    have you read the user manual?
     
  7. television

    television Always remembered RIP

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    From memory I had the same one as you and you cannot split the sides of the car, again the fully automatic version used a duo water valve but I am sure that your only uses a single valve.

    An owner will correct me if I am wrong on this :D
     
  8. OP
    ShivaYash

    ShivaYash Senior Member

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    Thanks T. Then why does it have two dials?
     
  9. OP
    ShivaYash

    ShivaYash Senior Member

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    I didn't find it helpful.
     
  10. huey

    huey Senior Member

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    Shivayash, I think the 2 dials only work with the heating, passenger side on 24 and driver side on 18 for example, regarding the dials where A/C is used I am not sure.
     
  11. Dec

    Dec Senior Member

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    The dial on the right point to the right (3 o’clock) for heating as in picture, turn this dial to the left for aircon (9 o’clock), as said one wheel for passenger side and one wheel for driver side, try it and see.

    Dec

    Edit, the centre vent (thumb wheel) needs to be open for aircon… I think.



    Picture source, different car, same principle… http://forums.mercedesclub.org.uk/showthread.php?t=26198

    [​IMG]
     
    Last edited: Dec 29, 2012
  12. DanF

    DanF Senior Member

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    I've just acquired a w124 with aircon so have spent a little time trying to work this all out and this is what I've come up with.

    The aircon works in parallel with the heating. First the air is airconned (or not) then the air is heated (or not).

    There is effectively a cold radiator (evaporator) and then a hot radiator (heater matrix), and the air always passes over both in that order.

    When the aircon is on, the cold radiator is turned on. This cools the air and the moisture in the air condenses on the cold radiator, dehumidifying it. This is the default position, no buttons lit.

    When the dehumidifying button is on (button lit), the aircon circuit (cold radiator) is turned to maximum power to provide maximum dehumidifying.

    When the EC button is on, the cold radiator is turned off so there is no cooling or dehumidifying; this is to save fuel.

    The air now passes over the heater matrix which warms the air as determined by the temperature dials left and right side to the vents. You can have hot left and cold right if you desire.

    The right side dial controls which vents are open, foot, windscreen or face level, best to leave to the right I find.

    The centre face vents are never heated so it is either fresh air if aircon off or cooled fresh air if aircon on.

    The left dial controls fan speed, the dot is fan off; the 0 is fan off and outside vent shut I think. I think its best to leave this on position 2.

    Finally, the recirculate button is used to prevent bad smells from outside entering the cabin, or to speed up the cooling or heating of the air inside the cabin. It it switches off after a certain time automatically.

    At least, that's how I understand it…
     
  13. sbryantgb

    sbryantgb Senior Member

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    I was going to wait for warmer weather b4 trying to workout how the a/c worked. But since this thread has been started it may as well be now.

    [​IMG]

    This how my switches are usually placed which means I have been running with a/c on. Is that correct?
     
  14. Dec

    Dec Senior Member

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    Yes correct, provided the EC light is NOT illuminated, that’s the side for winter that you have selected, the opposite side... 9 o’clock...is for use in Summer.

    My understanding is that the aircon is on if light is off but is not working as hard as if it were at 9 o’clock and Summer. The thumb wheel dials settings determine how hot or how cold the air is.

    Dec

    Edit; The left dial should be set to at least fan setting 1, your picture shows it at 0.
     
    Last edited: Dec 29, 2012

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