They didn't give me any details other than puzzledly coming back and saying that it was fine and they couldn't find anything wrong. I'll see if there are any test results on the invoice.
I'll drop it off at the dealer we bought it from after letting it bake in the sun for awhile. Normally it cranks out cold air before leaving the parking lot but now you have to get it rolling and revved up before it starts doing anything.
Thanks for the parts suggestions - I was thinking it might be something more involved like that.