Gas and Oil Home Heating Furnaces - no freon, bad sealing, old system, too expensive..$200 worth of freon, Whoh!

I hada group of service guys come out and they said that the system is old (1982 Lennox) and that the freon leaked out. Which is probablt true, because it was working last year. But to spend $200 and have it lose the freon agin seems a waste..is this really $200? Can I get it cheaper? Is there a way that I can seal it with a sealer myself? Or seal all the a/c line joints together better by tearing teh system down? Do I need to discharge the system even if no freon exists, or can I just start tearing parts and pieces apart, seal the system, rebuild, and charge up? I noticed that the system blew out some air when i pressed down on the suction side port valve (probably because it was running without any freon?).
thanks
markh

When you depressed the schrader valve, most likely what came out was freon and not air. Part of the freon laws was the imposition of excise taxes on freon, so, these days freon is quite expensive. You can't buy it unless you have an EPA certification. You know the stop leak stuff you can buy for car radiators? Well, they don't sell anything like that for freon systems. The leak or leaks could be anywhere, not just at the joints. It is very common for the indoor coil to be leaking on older systems. I wish I had better news to tell you.

You need an EPA certified person...preferably a tech...to fix your system. Letting "air" out of your system is negligently venting refrigerant to the atmosphere which makes you eligible for a $10,000 minimum fine. A tech is far cheaper.

A "group" of service guys? A new system would be a good investment in the long run. The system cannot be TOTALLY out of refrigerant. Also the most common leak points are the service gauge ports. They always need to be capped and they can be soap bubble leak tested.