On my W116, 300SD I always disconnect the electrical wires going to my heating water pump, which is right next to to the climate control servo. I believe it's job is to pump hot coolant through the heater hoses. I make a self made tool out of two 3-4 foot lengths of wire each with an alligator clip on one end and a butt connector on the other ends. I hook the pump up to the battery directly while filling the coolant reservoir.
I do this because my manual say's to. Is this needless or a good idea?