1980 Chevy Corvette

it could be leaking anywhere a hose or pipe is connected to one another.
or the compressor.

leaking out in a month is a very slow leak and will be hard to find.

have the freon removed from the system.
then get a small can of UV dye, get the pressurized kind
The ones I use are good for about 4 cars. so read the directions.

recharge the system and keep using the AC till it stops again.

now you have to get a UV light, i tried a cheap black light from walmart but they didn't work very good, so I finally bought a UV light made just for testing.

Now, be in a dark garage or at night, shine the light on all of the hoses, fittings, tubes, compressor, and hard parts of the AC system, the dye will have a green or yellow glow to it and that is where your leak is. dont be surprised if you have more than one leak.

My compressor has a small leak. I have another compressor that came in the parts bin that came with the car. The previous owner thinks that it works fine, but never put it on the car. Can I test the compressor before installing it on the car and if so, how?


Thanks

You can turn it by hand to make sure it is not locked up.
That is the only test you can do.