I agree with both of these other answers. It's illegal to vent freon to the atmosphere ( if you get caught it's a minimum $10,000 fine) more importantly it's a deadly gas. It's heavier than oxygen so if you breathe it in, it will displace the oxygen in your lungs and can very quickly suffocate you. Definitely contact a professional to have it removed safely

It's illegal to just release any freon that may still be in the tank. Contact a place that works on AC and find out how to have it removed and them dispose of it properly.

The only legal way to do it is to have a licensed professional capture the Freon for reuse.

Contact a professional. It is illegal, terrible for the environment, and terrible for your health.

I have a very old (at least 25 years or longer) industrial size a/c unit that was given to me. I have broke it down for scrap and all that is left is the copper tubing going into what looks to be the Freon tank. I want to finish breaking it down so I can sell the copper. How and what do I need to do from here?

Any thoughts? Thanks