A/C Help

Recharged my wife's 08 aveo automatic. Step dad is a commercial A/C repairman...never worked on cars. Recharge didn't work. Purged system and pulled vacuum on it for twenty minutes. When recharged second time have 40pounds low side 90 pounds high side. He feels high pressure switch stuck open. Is he correct? where is the high side pressure switch.
Any input appreciated. If I have posted this in the wrong forums, moderator please feel free to move it. Thanks Lenny

I have an 09, the AC pressure switch on mine is in on the right side of the vehicle (left side when looking under the hood) near the firewall, it is about 6" before the high pressure service port on the same line.