In a continuation from the above post:

Parked the car a work for 3 hours (in the sun, if that has any bearing on anything) with the AC system working prior to working.
Got into the car to do errands and the AC was not working again.
Parked the car for approx. 2 hours (in the sun) and upon startup, the AC works again.

Help!

P.S. I went ahead and bought a climate control unit from eBay this morning