Part numbers for climate control 300sd

Manual or automatic climate control.

I did not know that there were two types. I guess automatic it's suspose to be. These parts have been changed and I am having dificlty with the temp control. It's all or nothing and now that I have the hot water problem fixed I am looking into what I think will be a module problem. Both the conrole center in the dash and the temperature regulator (an electronic device under glove box) are both not origional and could be non corect parts. My heat runs wild and will not shut off the water untile I turn the wheel to MIN or the system to off so I am guessing my temp regulator is kaput. Ido wan't to check that I have the right parts in place first though before I go hunting another temp regulator. My benz shop manule makes no distinktion as to any thing else other than one type of system. I do not have a parts manule so am not able to say for sure what the crect part numbers should be. Thanks Bruce

The automatic climate control is mosty for US cars, some Euro cars had it but not many. In Europe the manual heat is prevalent; two large dial on the console instead of pushbuttons.

The manual for the climate3 control system is LARGER than the body and chasis manuals put together. The schematic for is is more complicated that most earlier cars entire wiring harness. It's a right pig.

But, in realist only two things ever seem to fail: the monovalve and the pushbutton assembly. The monovalve failure is way more common.

This sounds like a monovalve failure to me. When they fail you get full heat. When the pushbutton assembly fails you get nothing. There is one rare mode of failure when no heat means monovalve, btw.

If youcan you can look at pulses to the monvalve. It's pulse width modulated; if you can see the pule width change with no commensurate change in temperature, it's absolutely the monovalve. Tha brain is sending tghe right thing but that little bit of rubber in the monovalve, has, as they all do, torn and is always passing full heat no matter what the setting.

I really would try this first.

The hot tip for a pushbutton asembly is to get opne off ebay for $40-$60. They cost a fortune rebuilt and add a zero for new. Everybody buys used ones and they work great. I doubt this is your problem though.

I have checked the mono valve it is ok. I just got this car to heat by replacing the mono valve. I have fought this car each winter for 3 years now. There was a home made heater control system in it when I bought it. The controls have all been bought used to get it to start working again. Till recently this car would onl;y heat if driven under

30 mph and freeze you over 30 that was fixed by putting on another mono valve. Now I cook at all speeds. I guess that's better than freezing but I am afraid that I am going to start going through window motors now. When I hook a light to the valve I get heat with the light off and no heat with light on. My problem is I cook as I drive because the light never lights. If I turn off the heater the light is on. If I click the wheel to MIN the light is on. The rest of the time the light is on. The light will some times show some pulsing at first when you first start driving but soon it is solid off. I have ohmed out the sensors and they are in range of specs. I am just guessing but I think it would be the fault of the temp regulator (a part I have put on used) he is the guy that dose the pulsing I think. My regulator is 000 822 0903 and I have checked with one friend that has a 000 822 0303 this may make no difference but I am about to buy another regulator and would like to know if there is a difference between theses two parts. Bruce

BTW, those 2 wires going to the mono valve: One is hot all the time with the key on. The other is ground and that is the one that is controlled.

When you loose the light and get heat, that is when it is getting ground.

Ah. This makes a diference.

The problem I had and fought two years was fixed when I replaced the pushbutton assembly - everybody kept telling me to do this. I replaced the monovalve (not broken) the aux heater pump, dicked arond for years.

Then I replaced the pushbutton assembly like everyone suggested and goodlord the heat workls as advertised now.

Don't spend a lot of money one one. $50 max off ebay, but I would strongly recommend you get one and put thesystem back tothe way it was and start there; dollars to donuts it'll work just fine.

I could not agree more. I started with Ebay. This car had a manual hand valve for heat when I bought it and it had no AC at all. There was no module, no monovalve, no pushbutton. I have replaced all of its components with EBAY Great STUFF! Well I have had good AC for 3 years now it will drive you out. First winter had heat with regulation but it was a little squirrelly and some times would just suddenly run you out fallowed by a cold spell and then return to heating. Last winter that darn car would stop heating above 30MPH or over 2500RPM and return to heating as soon as you lowered your speed, it liked to drove me nuts but story turned short, a new mono valve kit fixed it. Now, well, I got heat! It could be the push button but because some times there is pulsing regulation for a few minutes (I drive this car with a light bulb across the mono valve these days) I get the feeling that what is supposed to be breaking the mono valve circuit in a rythematic fashion has gone bizirkoid. All seems to be able to work but it is just not willing to do it regularly. I am not positive but I believe the amplifier is the brains behind this function. Do you know? I probably plan to change the Module (amplifier) and push button both again. I have to wonder though if I bought this problem on Ebay? The parts worked at first but may have come with demons. I can buy a 000 822

0903 now for $40.00 I need to make sure this is a correct part first. It is the same part number I have in place now, I would hate to duplicate the problem over a part number being wrong. Well thanks for lending an ear. Bruce,