A/c in 2017 Buick Enclave not working. Is it under warranty?

Hello, your Buick is protected by a 4 year / 50,000 mile warranty that should cover most air conditioning concerns. The only exceptions would be items related to physical damage -- such as an outside source damaging wiring, or debris damaging the condenser for example. I would be hopeful that it is covered --- see your local Buick dealership for further guidance.