First, see if it will hold pressure
Next, hope the compressor works and see if the high side will hold even more pressure
Then, hope evaporator and condenser aren't clogged with debris.

To pressure check, have an ac guy "vac the system" and see if it will hold a negative pressure. If it does, have him charge it and add the appropriate amount of oil. Thens use it, see if the compressor comes on. If it seems to work, be aware that you will probably lose refrigerant slowly as your seals are most likely dry and brittle. Keep in mind, though, I had an '87 245 with an AC in perfect condition, and all it did was keep me from sweating "as much." I hate 240 Ac's, it seems the Swede's just couldn't conceive of heat above 90 or so.