[Neodeuccio]

Hey guys, I'm hoping someone can help me figure out an issue I'm having. I have an 09 335xi sedan, and the 3 highest fan speeds aren't working. When I turn the heat on, I have full control over the lowest 4 fan speeds, but if I try to go higher than that, the fan doesn't turn up, even though the display says it is. The funny thing is that if I hit the windshield defrost button, the fan goes on full blast, no problem.

I did a little reading and someone said that the issue could be a weak battery, but I had the battery replaced and registered/coded just a couple of weeks ago.

Help!

[Neodeuccio]

So last night on the way home from work my fan worked on all speeds. I spoke with a buddy of mine, he said the blower motor resistor in our cars doesn't use a traditional multiple-resistor setup, rather it uses pulse width modulation. As a result, it won't fail in the same way a traditional resistor will, and that the resistor is probably the problem. I found one on Amazon for cheap with a 1 year warranty, so I'm going to give it a try.

[Bmw1939]

On the fan there is a resistor or modulator of some sort. I can't remember exactly what it is called. You need to replace that. It's likely going out or the fan itself is seizing up due to water damage or age. Check your lower windshield.cover for cracks and make sure your cowling is all properly fitted.

[longm1985]

Idk if this affects you or the problem relates, but there's an open recall on mine for blower motor wiring.

However, I had this exact issue in a 2001 Pontiac. It was the resistor.

Our 2012 Mini had issues with the headlights not working in rain, and it turned out the headlight module was getting wet. While it sounds unrelated, it could be another possibility.

[e90yyc]

Yup—see if you're part of the blower motor wiring recall. If you are, you'll get the part replaced for free.

https://static.nhtsa.gov/odi/rcl/201...7V676-7418.pdf

[bobruh]

Originally Posted by Neodeuccio

So last night on the way home from work my fan worked on all speeds. I spoke with a buddy of mine, he said the blower motor resistor in our cars doesn't use a traditional multiple-resistor setup, rather it uses pulse width modulation. As a result, it won't fail in the same way a traditional resistor will, and that the resistor is probably the problem. I found one on Amazon for cheap with a 1 year warranty, so I'm going to give it a try.

Was it the problem? Having literally the same kind of issue