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Thread: AC/Heater

  1. #11
    Quote Originally Posted by Brett View Post
    Had another rainy day here so I spent some time on the car.

    Today I focused on seeing if I could get the HVAC system to work with no CAN connections.

    I had my doubts that it wouldn't work without the CAN connections wired in, but to my surprise the system worked.

    Well all most everything worked. The blower speeds didn't work. Blower just ran at low speed. Could be the control panel at fault. you can see in the picture that the display has issues.

    Even the actuator for controlling the direction of the air(up/down) worked and the duo valve for the heater worked(at least I could hear something working in it).

    Attachment 3857

    All sounds promising

  2. #12
    Quote Originally Posted by Brett View Post
    I always find it interesting how different countries(or even different regions of countries) call the same part by different names.
    I worked in the parts department of a motorcycle dealership and sometimes the manufacturers of the different brands of motorcycles had different names for the same part. Made it interesting sometimes trying to find the part you were looking for.

    OK back to the AC/Heater.
    Did some research and found out that "REST" in the display stands for "reset"
    I guess when there is an issue with the system trouble codes appear in the display and there is a procedure to reset the system to clear the code once the issue is fixed. Problem is, to reset the system you need the front control panel(or as Supermario's translation says "facelift").
    I guess this is when you need the CAN wires hooked up.

    Sooo close to having it working without the CAN system.
    Mopf means it's the facelift version of that panel (i.e. it was changed with the facelift of the C-Class/E-Class)

    And "REST" doesn't mean "reset". It's a "rest-heat function". When you shut down the engine and hit that rest button, the heating continues blowing warm air into the car using the remaining heat in the radiator. Good to have in winter to keep it calm inside, when you leave the car for just a short while. I was a testdriver for Mercedes for several years and I loved that function when I wanted to do a short nap...
    Never give up!

  3. #13
    Quote Originally Posted by Supermario View Post
    I was a testdriver for Mercedes for several years and I loved that function when I wanted to do a short nap...
    Nice to to have someone on the forum with some useful insider information
    Last edited by islandman; 12-03-2020 at 01:15 PM.

  4. #14
    Senior Member Brett's Avatar
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    Quote Originally Posted by Supermario View Post
    Mopf means it's the facelift version of that panel (i.e. it was changed with the facelift of the C-Class/E-Class)

    And "REST" doesn't mean "reset". It's a "rest-heat function". When you shut down the engine and hit that rest button, the heating continues blowing warm air into the car using the remaining heat in the radiator. Good to have in winter to keep it calm inside, when you leave the car for just a short while. I was a testdriver for Mercedes for several years and I loved that function when I wanted to do a short nap...
    Thanks for the clarification.
    I'm not familiar with the system (as you can tell)and any info about it will be greatly appreciated.
    That explains why I hear the duo valve working and the blower is at low speed.

    You wouldn't happen to know things to check to get the blower speed to work would you???
    I have a spare speed regulator that I changed out just to see if that would help but that didn't change anything.

    I'm guessing that the CAN wires need to be connected to the front controls for the rear system to work or that the shutoff valve is sensing the system low on Freon and that has shut down the system.

    Thanks again
    Brett

  5. #15
    You're welcome, Brett. Unfortunately I can't help with the blower speed control. I don't know any of those prototype builders at Mercedes-Benz personally, who would surely know how to get it to work. I try to ask some friends if someone knows anything and will post it here.

    Only thing I guess is, that when "REST" is activated in the car, the ignition must be switched off and thus the blower regulator is not working, because a fixed speed is set. You're AC/heater may still think the ignition is off, even though the display lights up. I have no idea how to tell the unit that the ignition is on though...
    Never give up!

  6. #16
    Senior Member Brett's Avatar
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    Quote Originally Posted by Supermario View Post
    You're welcome, Brett. Unfortunately I can't help with the blower speed control. I don't know any of those prototype builders at Mercedes-Benz personally, who would surely know how to get it to work. I try to ask some friends if someone knows anything and will post it here.

    Only thing I guess is, that when "REST" is activated in the car, the ignition must be switched off and thus the blower regulator is not working, because a fixed speed is set. You're AC/heater may still think the ignition is off, even though the display lights up. I have no idea how to tell the unit that the ignition is on though...
    You may have helped more than you know
    IF the system thinks the ignition is in the off position then maybe I need to get the EIS module and wire it in to send a signal to the climate control panel to let it know that the ignition is in the "ON" position.

    I went back to the yard a few days ago and pulled the main climate control panel from another W220( the W220 that the system came out of had the main panel already pulled)and wired it in. It displays "REST" also and doesn't turn on.

    Thanks
    Brett

  7. #17
    Maybe the ECU needs a diagnostics reader plugged in the OBDII port and 'reset'?



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  8. #18
    Senior Member Brett's Avatar
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    Quote Originally Posted by Supermario View Post
    You're AC/heater may still think the ignition is off, even though the display lights up. I have no idea how to tell the unit that the ignition is on though...
    You are 100% right.
    I started thinking about that and the EIS has CAN routed into it. So if the EIS isn't connected to the system then the system would think the ignition is turned off.

    Went to the yard and as luck would have it they had a new row of cars that nobody had touched yet and they still had the EIS with the key still in them.

    Wired the EIS into the system and IT WORKS. Don't even need the main front controls wired in either.

    P3180002a.jpg

  9. #19
    Brilliant, I can feel the smile on your face from here!

  10. #20
    Quote Originally Posted by Brett View Post
    You are 100% right.
    I started thinking about that and the EIS has CAN routed into it. So if the EIS isn't connected to the system then the system would think the ignition is turned off.

    Went to the yard and as luck would have it they had a new row of cars that nobody had touched yet and they still had the EIS with the key still in them.

    Wired the EIS into the system and IT WORKS. Don't even need the main front controls wired in either.

    P3180002a.jpg
    That's great! Glad I could help. It looks really good so far.

    Cheers Mario
    Never give up!

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