Hello,

My two cents worth.....

I have also tried to get schematic for the 300e climate control unit. I was told the last year for available schematics on this CCU was 1982, which I have a copy of. Call Schiff European Auto, 1/888.789.6882, they have schematics for Mercedes........ http://www.schiffeuropean.com/ However, not for the 300e/w124.


I have had exactly the same problem as you are expericing.

My solution was to get one off Ebay, and make sure you can return it ,if it doesn't work. A lot of stuff on Ebay is very flacky, leant by experience.

Then remove the Aux water pump [AWP]. Install straight threw pipe in its place. It dosen't make any noticeable difference to my heat. The aux pump can fry your CCU. Mine was leaking anyway. They are none fixable, mine wasn't amyway.

Second option go to http://www.programainc.com they have exchange units for around $235 with a 3 year warranty. There install instructions have you check the aux water pump before you hook up the CCU. It says no more then 1.5 amps draw on the AWP.

Its a bad design really I think, they should have installed a Aux relay to drive the AWP and the Mono valve. But i guess when its new it probrably OK!

Good luck

Brian