My blower fan for the a/c keeps ramping (blows high, then low) up and down non-stop. It just started doing this a few days ago. At one point today, the fan wouldn't even turn on manually. Then finally it decided to magically start blowing but was still ramping up and down. What the heck is wrong? HELP!

 

Sounds like blower motor regulator/resistor part #67636988452. It is a b!cth to get to but you can do it yourself. I changed mine aswell as the blower itself. I would recommend some diagnosis because it is a big job so you don't want to get in there, do all that work and that wasn't the fix.

 

Well the weird thing about it is it just started happening right after I got the car back from the dealer for the battery cable recall. Prior to that, I had no problem at all. I read where someone said the system may just need to be reset.

 

I was having this same problem, however ever since I replaced my battery it has never happened again. If it only started after having the battery cable replaced, then its something to look at...

 

yeah this other guy online said he had to charge his battery and it never happened again. my battery is only like a couple of years old. i think i will try to charge it. the other day when i was trying to get it to stop ramping, it then did not want to turn the fan on period. not even manually. but after about five minutes, it magically started blowing. weird.

 

+1

This happened to mine as well

 

and you resolved it how?

 

Installing a new battery. Basically the symptom was the air being slow at stop lights, then it would start pushing more air out when running on the highway, etc. Everything functioned normally after installing the new battery.

 

Not sure if it was the same issue but my defroster would come on full blast at random times when I had hvac set to auto. First they replaced the resistor and issue continued. Went back and they determined the condensation sensor was "giving an implausible signal" and they replaced it. Part number 64116928326. It has been a month and the issue has not come back

 

Did your blower not work at all sometimes and then magically start working?

My indy mechanic said check the fuse but he didn't know that it blows some of the time.

The service manager at the bmw dealer said it sounds like the regulator. He said its underneath the dash.