Reverse + A/C = Duster Dies?????

Hi There, I'm having a kind of a strange issue going on with my /6 Duster. When the A/C is on and I shift into reverse the car idles a bit and then dies. To start the car again I have to turn off the A/C because if I don't the car wont start. This issue doesn't happen all the time but it bothers when it does. Why this could be happening? What should I check over in order to correct this? Any help will be appreciated.