on my 1995 850T, the front windsheild defroster stopped working. When I turn the dial to defrost the window, nothing happens. I tore apart the dash because the Volvo dealership said they put a new damper motor( or vent door motor) in and it was working, but would not open and close the door because they said there was something jammed inside, so thats why i tore apart the dash, but found nothing jamming up. It was quite free actually.
Anyways next I checked the voltages going to the motor. 1 wire is a ground, 2 wires read 5V and 2 wires read like .8V, so like nothing. No matter how I switch the dial I am not gettting any reading from those 2 wires. I tested the voltages on a motor that is working, and same thing but one direction I would get 10V on one of those wires without reading, then 10V on the other wire when the dial is turned the opposite way.
I have continuity from the motors to the climate control unit. I have replaced the unit with one I know is working.
Is there any sensor or relay that may cause this problem????