Wife's car sometime it comes on works good sometime it won't come on took it to shop and of course it it worked
Freon good every thing checks good don't want to take to dealership 2014 gmc terrain

Any suggestions 🤔

Describe coming on and off. The blower motor isn't blowing? The air blows cold then hot then cold?

Sounds like compressor. How many miles? If it has a few miles on it, the distance between the clutch and the clutch pulley may have too much clearance. Therefore, when you hit a bump, it kicks back on...The only way to tell is when it quits cooling, look at the compressor and see if the clutch is engaged. If not, tap the front of the clutch and it should engage. Seen a ton like that!

Yeah on an off need to be defined. As described above it could be the compressor clutch. It could also be a blend door.

What grasshopper said??

Replace the low pressure switch on the AC compressor. This is a common problem on GM AC systems.