re: 92 400E. I'm getting the "Electromagnetic A/C compressor clutch blocked" on the base module/pin 8. AC used to come on for a few seconds, then cut out, now it won't come on at all. Freon level is OK. I thought I might try a new hi/low pressure switch largely because it's cheap.

But my question is this - is it possible to replace this switch without evacuating the system? It looks pretty easy to get it out and throw a new one in right away, but I have very little knowledge of AC systems. Is all hell going to break loose when I take the old one out, or some other environmental disaster? If the system has to be evacuated it probably makes sense to switch to a diagnostic approach to the problem.