Just bought a 1990 190e 2.6 from the local MB dealership in Bend, OR. Very nice car which they sold new and took back in on trade. 81,000 miles.

Problem: When I bought it, it had a leaky auxillary water pump (little pump over the passenger side fender well under the hood). As part of our purchase agreement, the dealership ordered a new pump and installed it for me. Once the new pump was plugged in, I lost all power to my climate control system, which was working properly with the old leaky pump. When the new pump was unplugged, everything started working again. The service dept. determined that the new pump's wiring must be bad, so they ordered another one. When the second new pump arrived, it did the same thing. The service manager explained to me that I must have some sort of electrical problem in my climate control wiring that is causing it to shut down when the auxillary water pump is plugged in. He said that it could take some time (and of course $ in labor) to track down the problem and since the system works fine without the auxilliary pump, to just keep it unplugged until I have the money to fix it, or track it down myself. (it should also be noted that the car has a brand new main water pump and thermostat which seem to be keeping everything running ok, even without the help of the auxilliary water pump). The service manager told me that as the weather warms up this summer, I could experience overheating unless the auxilliary pump is working, although, he said it could continue to be fine without the auxilliary pump.

Question: First of all, do you have any idea what the problem is? Second, am I ok to keep driving the car, provided I always keep a close eye on the temperature. Any help you can give me on places to look or things to check which could save me shop labor hours would be very appreciated. This is my first MB and I am far from mechanically oriented, although my father is both a mechanic and electrician and is willing to help. No experience with MB cars, however.