pressure switch

Hello all, I’d really appreciate AC help when possible, please. I’m in rural Maine and no shops are confident to tackle this. *So—can I change the Pressure Switch/Sensor without releasing freon? Bell Lexus says there’s no Check Valve in the compressor. Bummer. Is there a shader valve instead...

it appears on my 77 fj40 that the oil pressure switch under the oil filter is connected to my distrubutor to ground it out if oil pressure goes down.. is this normal?

I'm considering adding an adjustable pressure switch to the onboard air compressor. The goal is to have an adjustable air pressure switch so that I could change the cut-off pressure to suite the tires. Let's say it cuts the fronts at 35 and the rear at 40 or 45. This means I can be free to do...