I have a 2000 bmw 528 it and sometimes when I crank the the car up the fan will just blow....It does not respond to the climate control panel at all. After about 30 mins of being cut off the a/c will work fine. This use to occur about once a month however it is occuring more ofton now.What does this problem sound like?
what does your outside ambient temp read in your mfa? if it's reading an extremely low temp like -40F it's possible that the sensor in the front passenger wheel housing could have been damaged from a parking barrier or from this past winter in the snow. the car would be thinking it's too cold outside and for AC and to keep from damaging anything it doesn't allow for the ac. if these aren't any of the symptoms you're experiencing i don't know what it could be.
It sounds like the final stage resistor that BMW has redesigned about five times it seems. Extremely common E39 issue and easy to fix. I'm sure there are other forums with DIY write-ups, but if you search the E39 section of the M5board.com site for "FSU" or "final stage resistor", I think you'll get what you need. Here's one thread I found for you: http://www.m5board.com/vbulletin/e39-m5-e52-z8-discussion/148246-my-fsu-bad.html The part in question is (at least on the M5) is #3 in this link.
If it's your FSR, I would reccomend pulling it and taking it in to the parts supplier to get a replacement that matches. The first replacement FSR I got (Myele) was not compatible electrically. As soon as I plugged it in, the heater fan blew full blast, no matter what the setting of the Climate Control. Fortunately, BMA allowed me to return it (even though it was an electrical part). We had to try two other part numbers before we got the right one - the one with the BMW logo in it, made by Valeo (see my post in a previous thread about the FSR). Since replacing it, my Climate Control problems are history... and no more waking up to a drained battery courtesy of the faulty FSR. It's been more than a month now. I think with the E39 FSR, the rule should be: If it's original - replace it. Period. You can replace it yourself if you are willing to dive headfirst into your passenger footwell and pull two cover panels. Not worth paying an hour of labor in my opinion. There are some good DIY resources on the web for this. Also, the fact that your Climate Control does not work properly at first, but then does after driving for a while, should lead you to suspect low battery voltage. When my alternator was bad, I thought my CC was bad.
Honestly if I had a newer car with an FSU, I'd be very wary or replacing it with an OEM one with the BMW logo, because for obvious reasons, those are flawed...
I think it was the older ones that were flawed or failed (mine was date stamped 2000). The Valeo unit did not have a BMW logo, but it had the letters "BMW". I got it from BMA auto parts. If it only lasts for 10 years, I will be fine with that.
