What would make the rear ac quit working all of a sudden The fuses are fine?

That happened in my 1983 Mercury Villager and the problem was a blown circuit on the A/C circuit board. I soldered it and it worked. I found this solution online but I don't have the URL. Sorry. You have to remove the A/C unit from your dashboard and you'll find the circuit board there. The blown circuit will be near the corner of the board. Good luck!

I had the same problem, I went to the link below and clicked on topics. You'll find a detailed fix that costs nothing, worked perfect for me. Good luck. http://home.earthlink.net/~vqfaq/