You did a great job checking things
That is the cycling switch, here's where it is on my 95
The purpose of this switch is to read the lo side pressure and cut the compressor off briefly in order to keep the evaporator core from freezing over. It is not uncommon to have to change it once in a while.
To check for a bad switch, yes you can jump the connector terminals but don't just leave it like that. This can cause high head pressure in the compressor = bad. The switch simply unscews off of a schraeder valve so all you should get is a slight puff of refrigerant.
Also check the connector - sometimes the wiring is bent down sharply by the hood and after many years can get a slight break. I had this issue on my 95. After replacing a switch and then having another problem I re-pinned the connector and all has been fine.
Very short cycling as you mentioned can be caused by low charge but this needs to be checked with gauges to be sure. Generally, the lo side pressure runs at 25-35 psi and the hi side runs 277-300 psi but can vary based on condition and outside temps. If you add refrigerant, do no add the r134a cans with oil or leak sealer. That's the wrong oil for these systems and the stopleak is like fix-a-flat inside the system, often plugs up the orifice tube and does nothing for a leak.