leak to rear air cond. how to repair.,shop said dont know where leak is. on 2001 Chevrolet Express 1500

shop said in rear for sure. Can this be repaired easy or must go to professonal.

I don't recommend trying this one yourself. Dual AC systems can be a nightmare to service, even in a shop. If you don't know exactly where the leak is, and you don't have any leak detection equipment, you're just asking for trouble.