You likely have a fuel vapor leak all the time but notice it more when in A/C mode and especially if initially using recirculation (recirc) as less outside air to dilute the scent of same. Obviously you should have the root cause diagnosed and remedied as soon as possible. Probably just a leaking hose/connection somewhere in the line from the tank and a pro shop should be able to trace.
Of course any part can wear/fail over time, especially if O-ring deteriorating ethanol is in one's fuel.
btw: In the 1960's-70's many USA vehicles, especially station wagons, had a slight wisp of gasoline and similarly more noticeable once A/C was then becoming more widely adopted. But thanks to tighter manufacturing tolerances, better materials technology and quality control this is now a rarity.
Of course any part can wear/fail over time, especially if O-ring deteriorating ethanol is in one's fuel.
btw: In the 1960's-70's many USA vehicles, especially station wagons, had a slight wisp of gasoline and similarly more noticeable once A/C was then becoming more widely adopted. But thanks to tighter manufacturing tolerances, better materials technology and quality control this is now a rarity.
