AC problems in the Florida heat! HELP!!!!

[Beamernewbie]

Hi everyone as you can see I don't post on here unless I'm having problems however I do stalk Lol. My wife 2006 X5 is experiencing an AC problem. When you first start the vehicle and the AC comes on 98% of the time it blows hot air. After turning the unit on and off and rolling the windows down a little it starts blowing cold and usually works fine for the remainder of the trip. She works 10 hrs a day and when she gets in to head home she has to go through the same process again however if she is running errands and only leaving the vehicle for short periods of time it will usually work fine. I could really use some help on this as we all know " A happy wife A happy life" Thanks in advance.