There is a shrader valve so there is no need to evacuate for the low pressure switch replacement. Cleaning the connectors also helps I noticed. Mine was intermittently working and not working so I ended up replacing it. Also when my clutch would shut off, I could physically push the AC clutch and it would engage, so the shim that was behind the pulley was worn down. Took it out and compressor engages and disengages when it should now.
Low pressure switch is on the passenger side on the side of the evaporator near the bottom.