A/C fan speed control: only works on highest speed

[wikkid]

1991 318i.
A/C works (yay) but ONLY with fan speed knob turned all the way up to highest setting. Nothing at all on lower speeds. (not that I care now in July, but it's the same w/o the AC turned on, so it will be a similar "all or nothing" blitz of heat, come wintertime).

Is the switch the culprit? Is it tough to pull it and swap in a new one?

[jlevie]

The fan resistor is bad.

[fronton]

Search. This is one of the most common DIY questions on the board. Your blower resister is blown or corroded. You have to pull the splash guard HVAC panel off from inside the engine bay, remove the blower shielding, and pull the small 2"x1.5" resister with exposed springs out. If they are in tact, clean them very well and you may get another 20k miles out of them. If any spring is snapped or too corroded to look new again, replace it with the OEM part for $30.

[E30Gus]

Or the fan brushes are worn out.

[wikkid]

Thanks to you both.

I searched for about half an hour, but got only tons of unrelated hits. If you don't know to search for "resistor," then you can search.... and search....

[Poorboyz]

The fan resistor is bad. Speeds 1-3 go through the resistor, speed 4 does not which is why your fan blows on speed 4 and not the first 3.

Something like this.

http://www.pelicanparts.com
64-11-6-912-633

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