Have you checked the pressure switch? I think the A/C command goes from control panel to pressure switch to PCM. You should get a schematic of the truck and probe to see where the signal is being lost rather than parts swapping.

Looks like a sticky TXV. If there is severe water contamination, water can freeze in the TXV, but more likely the valve is just bad. Replace the drier too.

Put interior fan on low and rev the engine to see what the compressor is regulating the low side to.

You would use basically the same wiring for either setup. The expansion valve system cycles the compressor based on a temperature sensor on the evaporator. The orifice tube system (aka "CCOT" -- Cycling Compressor / Orifice Tube) cycles using a pressure switch on the accumulator. Either sy...

Consider a V5 or V7 variable displacement compressor, it is the modern equivalent to a POA system. The wiring is very simple since you just need to turn the compressor on and let it run. A high-low (trinary) pressure switch should be installed in the high side line to protect the system against over...

Yes temperature low at first then rises as the engine warms up really suggests that there is reheating. Check the evaporator outlet line like Jag987 said. Ideally, measure it with a thermocouple. The whole evaporator will be about that cold, so if it is a normal temperature of around 40, the air mus...

The code 66 mechanism is to prevent damage from the compressor continuing to short-cycle before the car is serviced. You need to clear the code from the computer before it will let the compressor run again. Disconnecting the battery for several seconds with the key off should work. If the shrader va...