If it has no belt that may be because the compressor is frozen and last own took it off so as not to cause problems. You check by hand to see if it is free. If it has oil in it, it should be OK. Unfortunately, you do not know how much is there without draingin and refilling (should be around 8 oz of PAG oil).

You disconnect the compressor wire at the connector near the compressor and carefully (so as not to ground the wire on anything) run a jump from it to the battery + terminal to see if the clutch is working. Once you know the compressor is free and clutch is working then you can put on a belt.

Like last post says you may need more than one can of R134A (if system is empty) before the pressure switch (up by the reciever dryer can at the firewall) will engage the compressor clutch. You can check the switch with an Ohm meter (or continuity tester) to see if it is working (continuity if OK).

If the system is empty it should take about 32 oz of R134A. Remember, you can get 11 or 12 oz cans much cheaper then the ripe-off 3 oz cans. If the compressor cycles on for about one second repeatedly, then you don't have enough R134A refrig.

There are a lot of post this time of year about air conditioning. You might want to do a search on the brickboard and get more information than from this shade tree mechanic.

Gary