it does sound like the pump burned up due to a climate control system vacuum leak the pump will cycle too often and burn up the little pump motor inside, you might get it to wok again for a while by spraying some lubricant inside the pump area, does it run?, the 2 unfortunate parts of repairing the problem is for that model the two elements that usually cause this probem are so far into the dash that it has to be removed, and the second part is the price of the pump, usually close to a few thousand dollars, i guess you could get a new pump and disconnect and plug the climate control supplement vacuum line from the unit. what is the part number for your pump? bosch and mercedes if given? i will see what i can find.
Ray