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W211 E270 CDI 2004 blows cool air when idling

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by morphix, Feb 10, 2020.

  1. morphix

    morphix New Member

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    Joined:
    Feb 10, 2020
    Your Mercedes:
    E-class W211 270 CDI
    Hey there fellow drivers, so recently I have ran to this issue.

    To explain it as clear as possible, problem is that when car is standby (idling, not driving), heater blows cold air no matter what position it is in.

    When driving the car, all heater functions work as expected, hot air blows, but as soon as you stop and wait for a bit idling, cold air starts blowing (even though the engine is already warmed up and at working temperature).

    I have read about heater control valve issues on this model, however I'm not quite sure if it is the case here, since people with broken heater control valve usually have no hot air blowing at all, while I do (when driving).

    Any suggestions are appreciated!
     
  2. LostKiwi

    LostKiwi Senior Member

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    Location:
    Midlands / Charente-Maritime
    Your Mercedes:
    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
    Sounds like the auxilliary heater pump has failed - quite common.
    Not sure where it is on 211 but on 210 it's drivers side just below and behind the headlight.
     
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  3. DREAMER NO2

    DREAMER NO2 Senior Member

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    Your Mercedes:
    W124 2.6E M103 1989
    Lostkiwi I will second that ..
     
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  4. OP
    morphix

    morphix New Member

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    Your Mercedes:
    E-class W211 270 CDI
    Cheers for the insights! :cool: I will look for a new aux heater pump and update this thread once I've made progress replacing it.
     
  5. LostKiwi

    LostKiwi Senior Member

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    Joined:
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    Location:
    Midlands / Charente-Maritime
    Your Mercedes:
    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
  6. OP
    morphix

    morphix New Member

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    Joined:
    Feb 10, 2020
    Your Mercedes:
    E-class W211 270 CDI
    Alright, finally managed to get some spare time and replace the auxiliary heater pump. On W211 270CDI it is located near the SBC block (not visible in the borrowed picture, it is a bit deeper). But the repair itself is not that difficult, took me about 30 minutes. It is just a bit hard to remove hose clamps from it since the space is tight.
    [​IMG]

    Anyways, heating now when standing still and idling seems to be back, everything works as expected. Thanks!
     
    daibevan likes this.

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