BenzWorld Junior Member
Date registered: Oct 2013
Vehicle: 1985 Mercedes Benz 300D
Location: Everson, WA
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W123 Inconsistant cabin heat, slight engine temp fluctuation, wire on thermostat cap?
Quick question here. I've got an '85 300D Turbo. I bought it about a year ago, and am finally getting it out of the yard and onto the road.
I knew it had this problem when I got it, but now I'm experiencing it, and not completely sure what the deal is.
The cabin heat comes and goes. Nice and hot when it works, then ice cold. When the cabin heat goes off, the engine temp goes up a few degrees, to about 85c. I unplugged the monovalve, which I understand is supposed to open up the coolant flow to the heater core and give me full heat, but it was still coming and going.
I'm kind of thinking the thermostat is a likely suspect, and a good idea to replace anyways, but there is a wire that was connected to the thermostat housing that is broken off now. I know it's not the temp sending wire, as that one comes off of the head. So what is this wire coming from the thermostat housing? Is it a temp sending unit for the aux fan?
Any thoughts would be greatly appreciated. Thanks!