Not sure about your particular pressure switch, but the ones I've seen contain two switches, therefore four wires. One switch cuts out the compressor when the pressure is too low, and the other pair cuts out the compressor when the pressure is too high.If you can check with a circuit diagram what the normal operating condition is, then unplug the switch, and as Colinv says, use paper clip or bit of wire to let the system think the pressure is correct and check if it works correctly.All you are doing is bypassing the pressure sensor to see if things work properly without it, and thereby seeing if it is what's causing the problem.But at least we all think you don't need to de-gas the system.
