no need, all you need to do is take out the climate control unit, disassemble it's case, extract it's mainboard, scrape the protective enamal off of the solder joints of a specific capacitor (a blue rectangle on the back of the board), and re-solder it with some extra solder. Plus, you can clean out it's little temperature reading duct while your at it, it gets all caked up with dust and gets nasty, especially if your a smoker. http://www.macadamizer.com/bmwfix.html
This guy replaced his capacitor, but either way, the solder joints have barely any solder on them, and from all of the heat cycles of the components heating up and cooling from daily use created stress fractures, particularly on the leads to that capacitor, which causes the CC computer to go nuts.
.... Of course, if you dont feel like doing that, you can always ebay one and watch it eventually go nuts unless that owner did something to fix it. Same goes for a brand new one, it too will probably eventually go nuts.
Or, if you want to, you can mail it to me with paid return postage and I'll fix it for you for 5$. No garuntees, but it wont be any worse.
I also betcha didn't know your car has motorola chips in it either, didya? :P