So, I think the pressure switch for my A/C is bad. The part is cheap, but does it involve evaluating and refilling the system? Or can the switch be replaced without doing this?

 

Nope. Any time anything like this need to be replaced it has to be evacuated and replace the switch. Then you have to put a vacuum on it and then recharge it.

Only a pain if you don't have the equipment to do it.

 

Many cars have a schrader valve under the dual pressure switch so that the switch can be removed without evacuating the system. So, I pulled out my service manual and it doesn't say one way or the other. It does show a gasket under the switch that is not a reusable item - if that means anything.

I would not suggest removing the switch as a way of finding out.