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W203 cabin temperature control issues

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by Dariow203, Oct 17, 2020.

  1. Dariow203

    Dariow203 New Member

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    Your Mercedes:
    W203
    Hi All.

    I have a w203 c270.
    I had the air con gassed by an approved dealer.
    Had the air con running awesome for about 3 months.
    But now it's not blowing cold air. There is pressure in the system.
    Other issue I have picked up. When the dial is turned full down for temperature. There is warm air coming out the vents. If I turn it up 2 small clicks up, then the air get cooler. But not cold.
    Please could someone help with this issue.

    Thanks in advance.
    Dario
     
  2. umblecumbuz

    umblecumbuz Senior Member

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    Location:
    Wales and Gozo
    Your Mercedes:
    S204 and CLC 204 cdi, other non-Merc machines
    Could be stepper motor problem. They stick sometimes. Malcolm (now sadly departed) had a kinda fix for that. I'll check my own archives to see if I can find it.
    If that is the problem, then if a simple 'fix' does not cure it, it's a dashboard out job.
    Hopefully someone will come along who has better info than I've given here.
     
    Last edited: Oct 17, 2020
    s5tuart likes this.
  3. OP
    Dariow203

    Dariow203 New Member

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    W203
    O man.
    Any help is much appreciated.
    I have stared to remove some of the dash to see if I can fix it.
    Thanks
     
  4. Oldspanners

    Oldspanners Senior Member

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    Location:
    Normandy
    Your Mercedes:
    C CLASS 2004 C180
    The stepper motor problem is usually signalled by a clicking noise from the dash area on start up which goes away eventually. It can be one of the six motors or one of the two operating arms that break. The parts are cheap but it is a bit of a job to get at them but can be done in a morning/afternoon.
    Plenty of info on youtube etc. I managed it so it can't be difficult;):)
     
  5. OP
    Dariow203

    Dariow203 New Member

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    Your Mercedes:
    W203
    OK.
    Great.
    Let me check it out.
    Thanks
     
  6. Rory

    Rory Senior Member

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    Location:
    Cheshire, UK
    Your Mercedes:
    2005 C270CDi Avantgarde Estate
    Mine does something similar. To be honest, it's never been very good (I've had the car since it was a few months old). Dealer and indies have looked at it without any improvement, although basically all they do is say "no faults are showing". I had a new condenser a couple of years ago but I'm not convinced there was anything wrong with the old one.

    I've noticed that if I have it on face level vents only then the left side (inc the middle left vent) does get properly cold but the right side is a few degrees warmer - so I suspect warm (or ambient) air is mixing in, perhaps because one of the millions of flaps is not closing fully or because of an issue with the controller.

    What the above poster may be referring to from Malcom is the flap reset procedure, but I think that's more to do with the direction flaps rather than temp. I've done it a few times and it made no difference.

    From Malcolm:

    To reset heater flaps and actuators

    Switch on ignition.

    Press recirculated air and defrost buttons on control panel together for longer than 5 seconds.

    The LED's in the defrost and recirculated air buttons flash alternately.

    Wait until the LED's stop flashing (approx 30 sec) system set to defrost LED on.

    Switch off ignition.

    After 40 sec re start engine.
     
  7. OP
    Dariow203

    Dariow203 New Member

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    Hi.
    I did try that to.
    Will try it again and see.
    But makes sense that the position if the flaps could be out.
     
  8. joderest

    joderest Senior Member

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    Your Mercedes:
    ML270 2003
    as a thought, have you had the gas checked to make sure there is enough for it to work?, My ML would have a re gas and last up to 7 or 8 months before no cold air again, re gas and fine for another 7-8 months, then back to square one.
    I fitted a new condenser in the end, will find out next summer if that was the issue. When it was re gassed before, it would show a slight pressure, but not enough to work.
     
  9. OP
    Dariow203

    Dariow203 New Member

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    W203
    Hi.
    Yes.
    Did the gas and was really good for like 3 or 4 months.
    Kinda just good for the hot summer. Then winter it's down
     
  10. joderest

    joderest Senior Member

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    ML270 2003
    yes, but have you checked its still gassed, if it has lost most of due to a small leak the air con would not work
     
  11. OP
    Dariow203

    Dariow203 New Member

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    Hi.
    Yip still got gas.
    I'm making a tool today to measure the pressure.
     
  12. mioba

    mioba Senior Member

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    Joined:
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    Location:
    Nottingham
    Your Mercedes:
    W124/E200, W220/S320CDI, W205/C200, W251/R350CDI 4Matic
    What kind of tool.
    Get it checked properly, you dont want to be messing with AC gas lines.
     
    axelcls likes this.
  13. AnthonyUK

    AnthonyUK Senior Member

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    Your Mercedes:
    C240 estate 2002
    You can read the pressures with a Mercedes specific code reader such as the Icarsoft.
     
  14. OP
    Dariow203

    Dariow203 New Member

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    OK. Thanks gents.
    I was kinda thinking of just putting a pressure Guage on it and seeing the pressure.
    But cool. Will see. Thanks
     

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