I own a 2005 X5 e53 and can't figure out why when I turn my ac on it won't cool down until after I have driven for a good 10 minutes when the aux fan finally comes on. Sometimes I can get it to start faster by revving the engine but not always. The battery also has a dead cell if that helps figure it out. I checked all of the fuses and they're good. I also have the AC charged with freon to a bit over 35 psi.