99 malibu a/c leak

Wife has a 99 Malibu, Latest issue is an air conditioning leak. I have been trying to locate it for some time. I have used soapy water and a freon sniffer. I still can't find it. Does any one know of any common spots to check on these cars. I takes about a week to leak down, if that helps. Thanks in advance for your help

it is hard to find a leak with a freon sniffer. the best way to find a leak is to add die to the system and use a black light to find any that leaked out. they sell kits at autozone for 40-50 dollars.

V5 compressor shaft seal most common.