TS: go buy the dye from auto parts store, add it and charge some refrigerant. use the A/C as much as you can until the weekend.
Go over it with UV light and hope that you find the leak. pay special attention to areas around front tires(where they did alignment work). Depending on the size and location of the leak, it could take a day or two weeks before dye becomes visible.
From there, you legally have to wait until it leaks out naturally... or recover the refrigerant before you can open the system.