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The climate control stop working today. It stop responding, the buttons does not work. Your help is apprieated
 

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Just a few buttons stopped working ? or the whole module quite working? If a few buttons stop working, the buttons can be fixed with some 5 minute epoxy glue, and few small scraps of plastic.

Martin
 

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Just a few buttons stopped working ? or the whole module quite working? If a few buttons stop working, the buttons can be fixed with some 5 minute epoxy glue, and few small scraps of plastic.

Martin
All of the buttons stop working
 

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ohh.. That is nothing epoxy can help you with. Check your fuses. Pull the module out and unplug it. and reconnect it to reboot the microprocessor.

Martin
 

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Mine has done the same thing. Everything was working the other day. Today, the climate control unit is dead. All fuses including the fuses in the main control module are good. What control module do I need to unplug?
 

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I needed to bump this. I still have a dead climate control unit. I could really use a couple of good suggestions on this. With all the fuses working and the car only having 48K miles, I am thinking that it is just too much of a cooincidence that the climate control stopped working the day after replacing the engine harnesses. Although I just don't get why everything tested fine right after the harness change.
 

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As far as I can see, if fuses #18, 20 and 21 in the main fuse box are good, then you really need to take the a/c control unit out of the centre console and start checking that the two multi-pin plugs are properly in place and that the correct voltage supplies are appearing at the unit.

I assume that you have the unit with 2 small displays and 3 thumbwheels. If you do take out the control unit to check the voltages, you need to unplug the righthand connector (as viewed from the front of the control unit) and check the voltages coming in on that plug. Pin 1 is connected to ground so you should test that for continuity to chassis. Then there should be around +12V between pins 1 & 2, 1 & 11 and 1 & 20. If there isn't and the above fuses are all good, then you have a wiring problem. If there is 12V on these pins then I would assume that the problem is with your a/c controller. As I understand it, a bad a/c control unit will throw a diagnostic code, so you could confirm that yours is bad - or even start your trouble shooting - by having the codes read.

Mike

BTW, as I read it, pin 11 is hot at all times, but pins 2 & 20 require the ignition to be switched on for 12 V to be present.
 

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Thanks Mike :

Extremely helpful. So That would be the passenger side connector (US version) if I am reading correct.

If it went bad, then I have a concern that something I did to the wiring may be shorting it.

I also read that the resistor by the fan motor could make the unit dead? Is that correct?

Would you have a wiring diagram for this?

Thanks again
 

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Forgot to ask - how hard is it to get the unit out?
To answer your second question first, it can be a bit of a struggle but it doesn't require any special tools. The method varies slightly, depending on whether you have a one-piece or two-piece wood panel in the centre console - so that's your first question. The two-piece has a join on the curve just below the ash tray. If you hunt around on the forum you will find descriptions for removing both types - but let me know which you have. Part of the removal problem is making sure you don't crack or scratch these panels - they are eye-wateringly expensive!

I'm fairly certain that it will be the front passenger-side plug on the US version - I don't think there would be any reason to swop this around - and, come to think of it, my info comes from a US source.

The following are links to the 2 halves of the wiring diagram:

http://www.autolib.diakom.ru/CAR/Mercedes-Benz/1994/S350/SYSTEM WIRING DIAGRAMS/5120.pdf

http://www.autolib.diakom.ru/CAR/Mercedes-Benz/1994/S350/SYSTEM WIRING DIAGRAMS/5121.pdf

To the best of my knowledge - which is rather limited - these are the relevant diags.

As for the auxiliary fan resistor, if it went open cct, it looks to me as though stage 1 fans wouldn't work - but that's all. If it went short cct, it would cause the fans to run at stage 2 speed instead of stage 1. If it went short cct to ground, it would blow fuse #2. I can't see why it would lead to a blank control unit - which is what I assume you have.

Mike
 

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Hi - I recently am facing the same issue. My climate control on the my 2005 c240 stopped working. I am considering replacing the unit but thought to reach out and ask what your approach was to solving the problem. Appreciate the insight!
 

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Hi - My climate control recently stopped working in my 2005 c240. I am considering replacing the unit but thought to reach out and ask how you resolved the matter. Many Thanks!
 
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