Vent Selector Switch Stuck in Defrost!

[kickhams]

I live in Texas - it's almost summer time and it's time for me to deal with my vent selector switch being stuck in Defrost. So when I turn on the AC it only cools the windscreen.
I had this problem before and it was fixed when my battery died. After I recharged it the selector switch was working again(?).

Any ideas on this would be much appreciated!