W202 Climate Control Unit illumination problem - PeachParts Mercedes-Benz Forum

kameraguy · #1 01-05-2004, 07:40 PM

Hi guys,

I have a 1997 C36 and the Climate Control unit illumination has failed. The unit still works fine, but at night with the lights on, that unit has no backlighting.

I have the radio keys to remove the unit and I initially thought the bulb burned out on the bottom. I replaced it and it still does not work.

I am uncertain if the single bulb is the only one to replace. As far as I can see it's the only bulb that is serviceable. I'm not sure if that's even working.

Is there another bulb I need to change?

How about a fuse?

As a new unit costs $$$, and mine is technically working, I was hoping there was something simple I missed to get it illuminated again. It's crazy to poke at the console at night until I find the right button!

Thanks for any help anyone can provide.

Gilly · #2 01-05-2004, 08:24 PM

Usually it's just the bulb.
If you have a voltmeter, you can pull the bulb and turn on the lights and check for power accross the contacts, or try to ohm out the new bulb and see if maybe you got a bad bulb.

Gilly

kameraguy · #3 10-25-2004, 08:42 PM

May this thread rise above the grave!!

Ok, so believe it or not it took me THIS long to get serious about the issue. I decided to jump on a replacement climate control from an ebay seller as it was dirt cheap. $40!

I received the unit and it works great. Illumination is as it should be and for the most part everything is peachy...

Except...

Now I have this irksome behaviour with the replacement.

With this unit, whenever I turn off my car and restart it, the climate control will seem to always default back to 68 degrees with EC off, and the fan set to two bars above min.

With my original unit, it would rememberf myh last settings and keep them even after a restart.

For example, I prefer to leave EC on to keep the AC off unless I need it. And I usually set my fan to 1 above min and temp at 70. But whenever I turn off and restart my car, the replacement unit will go back to the settings I mentioned.

Now I don't know which model MB this climate control came from, but it does work for all features like a charm. It's just this behaviour i'mnot used to.

Is this normal? And is there a way to change it to remember my last settings? Any help is much appreciated. This is no major issue by any means, but after a while it's annoying as heck.

Heh, I should have known car problems are never fixed this easily :p

Gilly · #4 10-25-2004, 08:58 PM

I'd assume that this is why you got it for $40.
How about trying to swap the known-good bulb from this unit into your original?
Talk to ya again in 9 months!
Gilly

mpolli · #5 10-26-2004, 12:06 PM

I have read somewhere that when replacing these units that they have to have their configuration programmed or something like that. I forgot the exact language. Anyway, I believe that the dealer has to program it. Can anyone confirm/explain that? As far as your old unit with the bad light, I might be interested in that one since mine has a flakey display and maybe I can can use part of yours to fix mine. Let me know what you figure out.

Mike

Will_w202 · #6 10-26-2004, 02:11 PM

My 97 did the same thing over the summer and it was a simple bulb replacement. Remember, it's not impossible to get a faulty replecement bulb!

kameraguy · #7 10-26-2004, 04:17 PM

I will try and swap the bulbs between the two. Thanks for suggesting this as i completely forgot to even try. Hopefully I will get back to you guys in 9 hours !

mpolli, if i resolve my issue, i'll let you know in case you want to pick up my spare.

Gilly · #8 10-26-2004, 05:34 PM

Yes there is programming which is done, in the case of a ACC control panel, I believe the only thing that needs to be done is called "version coding". This is where you would enter data using the shop computer to specify the model car which the unit is installed into, in this case "W202", there may also be an entry for which engine is in the car, but this would be it. The control unit may also be used in other chassis, such as a W210 or W140, for example. It is pretty straightforward on this particular part, some computers require a great deal of this type of coding. I don't believe that any coding change would fix the problem at hand, I would still maintain there is a problem with this part and that's why it was removed.
As I said 9 months ago, in agreement with Will_w202, the replacement bulb may be a bad one, or it is misinstalled somehow. I'd TEST the bulb, or swap it with the known-good part.

kameraguy · #9 10-26-2004, 05:45 PM

Oh, Gilly I forgot to confirm I did test the replacement bulbs with a multimeter. They do work fine. I can't recall if I tried the bulb holder, but I must have as it is simple enough, but I will try again when i get home.

Gilly · #10 10-26-2004, 05:49 PM

Another trick is to try installing the bulb with the parking lights on, so that in theory the bulb should be lit. Sometimes the socket has "a sweet spot" where you get good contact and the bulb works, seen this before. Usually if you find a sweet spot, it'll work pretty reliably in that spot. You can also bend the contact tabs to get a better contact. Never replaced one of these for an illumination problem, hopefully you can fix it.
Gilly

kameraguy · #11 10-27-2004, 04:21 PM

Well, no change after trying again last night. My original one is still dead so it must be some internal failure for the bulb circuit. I guess i'll make an appointment with the dealership and see if they can reprogram my replacement. Hopefully my new one is not defective in this regard! Will update thread after I try this.

Thanks for the help guys. I appreciate it.

Will_w202 · #12 10-27-2004, 04:31 PM

You know, with my replaced bulb, the CC light still is the last one to come on when I switch on the lights. Usually takes an extra 2 seconds. Must be a dirty contact point in a switch or something.

mpolli · #13 10-27-2004, 04:56 PM

I noticed the same thing last night. There is a delay to turn on and a delay to turn off. I assume this is because the light is controlled on the CAN bus. So this could indicate that the connections for the CAN bus are faulty somehow. Or this could indicate that I don't know what I am talking about... I will see if my alldata diagrams (if any) can shed light on this.

Mike

mpolli · #14 10-27-2004, 05:08 PM

Yes. There does appear to be a connection to the CAN bus. So that could possibly be the cource of the problem.

Mike