a/c system

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...

So I'm resto-modding a Land Cruiser HJ45. Someone had put a Vintage Air unit in there, which worked fine, but then stopped cooling. The brackets were real hackjobs, with one of them attached to the exhaust manifold, and the compressor was bolted to the alternator, which made belt tension...