may not be right thread, heater probs

Discussion in 'Interior' started by mercjim, Sep 26, 2008.

  1. mercjim

    mercjim Member

    Messages:
    46
    Joined:
    Aug 10, 2008
    Location:
    Leeds
    Car:
    C200 Elegance '95
    ok... heater is warm constantly... wont turn up or down with either control nobs....

    its not red hot... but when driving distance... need to have either sun roof on tilt open or a window slightly down to relax the heat....

    any ideas?

    thx
     
  2. 230K

    230K Hardcore MB Enthusiast

    Messages:
    2,190
    Joined:
    Jun 1, 2003
    Location:
    Belfast
    Car:
    09 E320 cdi Sport Estate, 98 E300TD Estate, 99 SL 500
    hi

    Check your fuses, but most likely your duo valve. It can be cleaned and can be a success but you could end up needing a new one.

    230k
     
  3. coupe deville

    coupe deville Hardcore MB Enthusiast

    Messages:
    786
    Joined:
    Aug 21, 2008
    Car:
    93 E320 coupe sportline facelift
    hi black bettys new daddy welcome-- 90% its the duo valve, I did mine and now got perfect temp control. do a search for duo valve and read THE PARROT OF DOOMS POST-great post with pictures and although my car is a different model to his its still basically the same. I found it easier to take it out of the car to clean. dont use any oil or grease to free it. use something like servisol aero klene 50 from maplins electronics
     
    Last edited: Sep 26, 2008
  4. OP
    OP
    mercjim

    mercjim Member

    Messages:
    46
    Joined:
    Aug 10, 2008
    Location:
    Leeds
    Car:
    C200 Elegance '95
    awesome post by parrot of doom.... thx guys
     
  5. KillerHERTZ

    KillerHERTZ Administrator Staff Member

    Messages:
    16,632
    Joined:
    May 21, 2003
    Location:
    Cambridge
    Car:
    CLS63 AMG
    ignore, I didnt read all of the replies doh!
     
    Last edited: Sep 27, 2008
  6. OP
    OP
    mercjim

    mercjim Member

    Messages:
    46
    Joined:
    Aug 10, 2008
    Location:
    Leeds
    Car:
    C200 Elegance '95
    ok, cleaned duo valve out.... lots of residue in there....
    put it back together b4 a long trip from leeds to birmingham.....
    was exactly the same...
    so gonna open it up and see if there is more residue in there...
    thinking about flushing the entire system tbh....

    any more ideas?

    thx
     
  7. KillerHERTZ

    KillerHERTZ Administrator Staff Member

    Messages:
    16,632
    Joined:
    May 21, 2003
    Location:
    Cambridge
    Car:
    CLS63 AMG
    Early W202s are prone to having the heater control unit fail.

    Does your heater dial go up to 4 or the later 5?

    I had exactly the same problem, it turned out to be the dash control unit.
     
  8. OP
    OP
    mercjim

    mercjim Member

    Messages:
    46
    Joined:
    Aug 10, 2008
    Location:
    Leeds
    Car:
    C200 Elegance '95
    4 with the window demister on it....
    totally flushed the system... and still same...
    doesnt matter if i have the controls on cold or red hot...
    still filters warm air thru.... no cold, no hot...

    thx for help
     
  9. alibally

    alibally Hardcore MB Enthusiast

    Messages:
    220
    Joined:
    Jun 8, 2008
    Location:
    edinburgh
    Car:
    W169 A160 and Smart 451
    Will the temp change when clicked into either full hot or full cold? If it does and the heater won't regulate in between then the ambient cabin temp sensor mounted in the interior light unit may be faulty.
     
  10. OP
    OP
    mercjim

    mercjim Member

    Messages:
    46
    Joined:
    Aug 10, 2008
    Location:
    Leeds
    Car:
    C200 Elegance '95
    its the same temp all the time bud... no matter wether i have it on hot / cold... full blow or off.....
     
  11. alibally

    alibally Hardcore MB Enthusiast

    Messages:
    220
    Joined:
    Jun 8, 2008
    Location:
    edinburgh
    Car:
    W169 A160 and Smart 451
    Unplug the duo valve a see if it goes red hot. The valve should go to fully open if you do this. You could check the voltage at the duo valve. Thers should be a 3 pin plug . The center pin is a ignition live and the outer of the pins are a switched earth from the heater control panel. With the heater on hot there should be 0 volts. Full cold you should get 12 volts. A test light can also be used. the light will be off at full hot, on at full cold and if the temp controls are set to the middle it will flash on and off. If this all works fine then the heater control panel will probably be ok..
     
    Last edited: Oct 4, 2008
  12. OP
    OP
    mercjim

    mercjim Member

    Messages:
    46
    Joined:
    Aug 10, 2008
    Location:
    Leeds
    Car:
    C200 Elegance '95
    ok, thx again Alibally... tried the above with a 12 circuit tester, nothing... nada....

    does this mean the control panel is kerplunkt?

    all fuses ok... only thing that seems to work is the heater fan control knob.... & the heat directional knob
     
  13. vijilants

    vijilants Hardcore MB Enthusiast

    Messages:
    2,225
    Joined:
    Jan 23, 2007
    Location:
    London
    Car:
    C320CDI Sport W204
    The duo valve is fed directly from the control panel.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.