chevy driver

I am new here so I hope am in right place. I have a 92 camaro I bought that was not running. It turned out to be the security system which I bypassed. All was good till I turned on the ac and car died; would not start, no fuel pump, no heater motor. After scratching my head for several days I put 12 volts to heater motor plug and fuel pump came on and fuel came out of throttlebody injectors. After a few seconds it stopped. I tried to start the car and it started right up been running just fine since. What would the ac have to do with making the fuel pump quit? How would putting 12 volts back through the heater curcuit make the fuel pump start pumping? All is good again but I don't know what made this happen and ac is still not hooked up. Any ideas would be greatly appreciated. thanks in advance