My 2003 W211 E500 has blazing hot heat in the rear console vents even though the temperature in the rear is set to min (Max Cold) If I use the front control for the rear heat setting and run it up to max heat and back down to coolest setting cold air will come out for several minutes, but eventually back to blazing heat, I was told that the might me a magnetic valve under the hood that might be defective. If this is true has anyone had this repaired? and what was the part number and location of the defective part? Please help, Thanks again...