08 A/C Vacuum

I just purchased a 2008 and while I have the A/c on and accelerate to pass hot air blows out of the A/C vents. I am pretty sure it has something to do with the vacuum but I have no idea where to start looking.

All W-cars have vacuum issues sooner or later- look under hood- trace vacuum line (black plastic tubing) from intake source to vacuum reservoir- older models it ran right by battery where the battery acid corrosion would eat right through it- so I'd check there first...

Could also be a bad vacuum check valve.....