AC freezing up

No idea how to fix but if you turn AC off and just run fan on high you will cold air until it defrosts. Once that happens you turn AC back on. This works for home/office as well.

 

No trinary is a pressure switch, the thermostatic switch in the evaporator core kicks A/C clutch out when temps get to a set point.

The older ones are adjustable, and I try to set cutout at 30, and cut in at 33.

But my initial assumption would be that you're low on freon. At least I'd start there.

 

Just pull the two wires off the switch, and the sensor lead goes into the core. Easy to change, no need to remove evaporator or heater core.

 

Your truck is old and the evaporator is probably caked with years of dust and debris dust and mud pies under your dash all over the fins. Gonna have to pull it and clean it. I would just replace it. Easy job I just did in my truck a week ago. Maybe not easy for you

 

Normally they're held on with two screws. That one may slip onto a plastic attachment point. Yes, just put the lead back where it was, just needs to be able to sense core temp.

And Don above is correct. If you don't have enough flow across the core, they freeze up. Most older 379 HVAC filters have been removed and left out.