ac control

I posted this awhile back. I would like to be able to control the air coming into the cab with the heater/ac system. I know that the lariot has a recirculation button that works at all settings. I have an 05 xlt without this button. Only time you get recirculated air is when your on max ac. The last time I posted a guy said that he just closed the vacuum line and now it's always off. Meaning the air recirculates in the cab. I would like to be able to turn this on and off. Does anyone have any suggestions for doing this. Or could I get the switch from ford and install it if its an option.