"mm" wrote in message
...
Is it possible to tell if a roof-top AC still has freon in it?

Is there a gauge, or can I push a valve and open it a tiny bit and
hear if anything comes out? Or some other way. I figure they might
be empty already, and that's one likely reason why they don't work.

I"m cleaning out a building that is about to be razed, and it has 3
big AC's on the roof. Two are broken. The third was fixed 9 months
ago and probably still works. We don't want to vent freon, but if the
freon has already escaped, a friend and I would like to sell the
copper, etc.

Last week we took 1875 pounds of various metals to the scrap yard.

If it is a large unit, it should have two Schrader type valves where you
hook up the gauges. Window AC and refrigerators usually have a pinched off
copper tube. Scrap junkies often check by poking a hole, but getting caught
can be a big fine.