Hi all. I had some trouble with my heater blower fan recently, when set on speed #1
the speed of the fan would vary wildly. It would come on very weak (so weak the motor whined and squeaked from lack of movement) and then all of sudden it would blast air out like i'd set it to #5
. This also happened when set on speed #2
, but no others, which were working OK.
So I measured the voltage going to the motor using a multimeter, and it was all over the place (between 2v and 10v) rather than constant. So I figured the resistor/regulator to the motor was bad and bought another one. For completeness i also checked the control dials themselves (removed the control unit from the centre console, took it apart, and cleaned it with electrical contact spray) and also lubed and cleaned the motor itself.
So I got around to installing the new resistor/regulator today and it has fixed the problem
hope that might help someone out as i didn't find loads of info about my variable-speed problem, mostly just fans that were completely dead or dead on certain settings, but the cause seems to be the same thing. I think some of the resistors in the regulator are faulty, but not all of them, which is why it works on some settings
FYI part number for new regulator is 2108206210 / A2108206210, at least for the facelift R170. It is the same as a C-class W202 too i believe. I got a cheap no-brand one from ebay but the OEM one was Valeo i think