That green discoloration on your copper is a little bit worse than the typical light oxidation. Here is what John Palmer says:
"You should be aware that copper can develop a toxic blue-green oxide called verdigris. Verdigris includes several chemical compounds--cupric acetate, copper sulfate, cupric chloride, etc.--and these blue-green compounds should not be allowed to contaminate your beer or any other food item. To clean heavy oxidation, including verdigris, use vinegar or oxalic acid-based cleansers like Reverware Copper and Stainless cleaner."
So vinegar is still fine, but don't dilute it down much and make sure to get all those green oxides off your chiller before you use it.