A/C is not getting cold.

95 Olds Achevia S w/120000 miles, Automatic, FWD,
I just bought the car and had the a/c filled, oil, tranny and radiator flushed. They said the a/c was holding pressure. No leaks. Now its getting warmer and I can fell a very little cold air, not enough to cool the inside car at all. The blower works fine all speeds. I disconnected my battery for 3 minutes in case they didn't reset after the fill. (I do have an oblong computer plug in not the triangle computer plug in under the steering wheel.) What else could it be?
What could I check for and can you explain where and how I would do this.

It’s getting warmer out there.

Thank Yoy