We drained the system entirely so we could disconnect all the climate control hoses, the system was open at the little return pipe from the aux pump, the output port on the side of the engine, and the drain plug was out the whole time. I refilled it with MB coolant, the thermostat just seems to be stuck. If we can't get it to reliably open we'll probably just replace it....
As for the blower, not sure if its just the brushes, it sounds bad, like mine did when it went in my car. It bogs down and does bad noises. The whole motor is probably toast. The motor from my car was, it was burned and all loose and falling apart, brushes were almost flat....very sad. Ebay has them for $130 though, and I used one of those, they work fine.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)