Many of us wire in defeat switches. The purple wire coming out of your heater controls is the one which turns on the AC compressor. Put a switch in line with it and you can disable it when you want.
When I do the EATC mod, I use the rear fan output on the EATC head to control a relay so the compressor can be disabled by selecting "Rear Fan Off" on the Explorer EATC head. More details in teh EATC how-to on my cardomain site.