Why don't you add some Diet Coke the system while you are at it. I heard from a mechanic that it does wonders to HVAC systems.

Mike, I'm sure you are a nice guy, but . . .

intentional venting of refrigerants in not only illegal, but more importantly, it is wrong.

Adding more oil will not make your compressor run cooler.

You just said that the temperature sensor/switch is faulty. Why are you then concluding that the compressor is therefore running hot? If you know a "thermometer" is faulty, why are you then relying on that "thermometer" to make a critical judgement?

Although I have not played with this sensor/switch, from a picture I have of it, it is external to the compressor and is, therefore, easily bypassed.

I think, however, you have another problem. I don't think the switch is faulty at all. I think you system is low on refrigerant so what refrigerant is left is picking up too much heat in the evaporator and superheating to the point it is overheating your compressor.

But don't just go willy-nilly adding refrigerant. Bring the car to another shop and have an HVAC expert examine your system.