VW Touareg 7P 2017 Blower fan how to test

[shabazmo]

I have a VW Touareg 7P. The fan will come on for about 30 secs and then stop. I have removed the fan to the bench. It has a built in resistor and 3 wires feeding the fan. One is 12v permanent, one is earth and the 3rd is I think a pulse width signal which determines the fan speed.

Does anyone know how I can test the fan on the bench.

I have found out that I can run the fan on speed 4 indefinitely but when it goes to 6 or 7 it will cut out.

Given a new fan is £350 from VW and there appears to be no aftermarket fans available, I was wondering whether anyone can advise me how to test the fan on the bench, so I don't waste money on replacing a fan when the dash control unit is at fault.

[shabazmo]

I finally got around this problem. I decided to look at some “measured values” on VCDS. I came across blower voltage (specified value-Data), and blower current. When the blower is off, the reading is 0V and 0A. As the fan speed increases, both voltage and current rises until they reach about 10V and 8A, the fan then stops and the readings show 10V and 0A. I concluded that the motor was faulty since the control wire was still showing voltage. New fan fitted and its is a fix.

I am not sure how VCDS measures such a signal but at least it helped prove the fan was faulty.

[Crasher]

VCDS doesn't measure it, the HVAC controller does, VCDS doesn't measue anything, all it does is read controller data.

[shabazmo]

Thank you for that technical clarification. Much appreciated. Two other thing that are bugging me. Does the signal wire for the fan send out a PWM signal? and would I have needed an oscilloscope to measure the signal?