No Blower

I have a 1984 190 2.2D "201" The car has about 350 thousand miles on it and it runs and drives great. I have a few problems with some of the electrics on the car, mostly just have to wiggle the fuses to get the wipers going when they stop and giggle the dimmer control when the dash lights fade and so on. But recently the heater blower stopped, about a year ago it stopped and I had to install a new blower speed switch above the push button control unit and that fixed it. a few months back it quit again. I assumed it wasn't the blower switch being I installed the new one and used a new MB factory switch (the original one lasted until 1999) so I talked to a factory MB tech and he explained that he thought it had to be in my push button climate control unit. Last month I ordered a new push button climate control unit and installed it into my car. No Change. I installed a new relay. No Change. BTW I disassembled the old Climate control unit and did find some burned circuits inside on its boards before I ordered and installed the new one. I am also a Technician, but I work on boats and yachts and have been a certified Mercruizer technician for 22 years. Mercedes Benz seem to keep me puzzled most of the time! Thanks for any assistance you might provide and I am only in Nashville so Atlanta is not to far if I need a major repair!

Thanks, Chuck