Tarrawr

I recently inherited a 2005 mazda 3 SP23,159k miles.

Fan works, but will only blow hot air when AC is on. Light is on. Tried switching relays, no luck. Compressor is spinning when AC is turned on, and stops when turned off. I tried charging the freon with a can, gauge reads empty and wont take a charge from the can. Could it be a bad valve stem on the low? Or maybe a larger leak somewhere?

First couple days with the car it was low on gas. After filling it up and driving, I noticed a gas smell in the interior. No leaks noticable after being parked for a day. I popped open the back seat, and it does appear that someone has done work on the gas tank. Maybe pump replacement? No idea. The fuel smell is stronger near the access. Ideas?

Any help is appreciated. Thanks.