Honda Civic 91 Air Conditioner Help please!

Hello. I have been having a problem with my Civic for about a year now
and it has gotten progressively worse. Basically when I turn on the AC
I hear the compressor come on, at least I think I do, the engine idle
gets lower when I put it on, and then all I get is warm air. Its not as
hot as when I put the setting to heat, but its still warm.
About a year ago it used to give me cold air almost all the time. Then
six months ago sometimes it would start blowing warm air.
I took it to a neighborhood mechanic and he told me the compressor was
shutting off when the system got a little hot so I needed to replace
the compressor AND I needed to switch to R134 as well.
I found a coworker who then told me I did not need to spend the $900 to
fix the compressor as it was fine. He said they do not seize up.. they
either work or they dont work. They are not intermittant. True?
So he said all I needed was to refill the refrigerant as i was low. So
he filled it up with something called R12 Freeze or something, a
replacement.
the car has been blowing cold air for a few months and now, its only
hot air.
Im confused. Do I really need to replace the compresssor? Im pretty
sure it comes on because of the drag on the engine when I hit the AC.
And also is there no way to fill it up with original r12 or is that
against the law? I noticed when he flushed the system and put in the
R12 Freeze, it didn't get as cold as it used to. It was better than
nothing but it wasn't like before. If anybody can give me some
suggestions that would be great. I am dying in NYC with the humidity
and 96 degree weather!