PeachParts Mercedes-Benz Forum - View Single Post

LUVMBDiesels · #7 10-09-2007, 09:19 PM

Quote:

Originally Posted by Craig

If it's "heater hot," the monovalve is open for some reason. Maybe a bad monovavle, maybe a fuse, maybe a control unit.

I agree with the monovalve. You should check it and make sure that you have 12v across the connectors when you have the temp dial on MIN.

If you have 12V then it is probably the valve insert that has gone bad.
If not, then you probably blew the climate controller or the fuse. The fuse also controls things like the transmission kick down and the reverse lights so if the fuse goes you should notice other things "wrong" with the car.

The CCU can blow due to the Aux water pump drawing too much current and melting the solder. Do a search on CCU fixes to see how to repair it. It is pretty easy, but takes some time and a soldering iron.

To change a bad monovalve insert takes five minutes and the loss of a little coolant. You can get replacement inserts many places including on this site.

It is funny how my BMW uses the same monovalve but as never had an issue in 24 years. Wonder if I just jinxed it...