Ok.. A/C systems are kinda foreign to me. Here's the situation:
Yesterday, the system just quits blowing cold, but it is blowing. I've narrowed it down to a failed compressor clutch because:
1) the compressor isn't running withe AC on
2) the clutch will not respond when battery power is applied directly to its harness, both polarities. Engine on or off. No clack, no spin. Could it be a seized compressor and not just the clutch? You tell me.
The system IS charged, I checked.
My options as I see them now are these, in order from cheapest to most expensive, not including buying a new car.

1) I can buy a new clutch for the compressor, (btw it is a Hella HS18 compressor) for $100 but I THINK I need to crack the system open in order to install?
2) buy a whole new rebuilt hella HS18 compressor with clutch for about $270 which of course also means opening the system.
3) take the whole situation to shop for repair (not in my nature).

What to do? Can I just replace parts then take to shop for evacuation and recharge?

Can a clutch be installed on these WITHOUT opening the freon system?

Again, a/c systems are kinda new to me...