RConrad,

The CCU is the Climate Control Unit in the dashboard with the control buttons that operate the A/C.

Your 97 has a different CCU than my 92, so advice I may give you may not be exactly right. The best thing to do is to start a new thread with your specifics and we can all chip in from there! I think there are some diagnostics you can engage by pressing buttons on your CCU that may give a clue.

It appears to me that the CCU style was changed for the 97 year model, (beginning 09/1995), but using my knowledge of the 92, you should be able to unplug one of the wires (or both) at the pressure switch on the top of the A/C Drier canister right behind the LF headlamp and disable the compressor.

If the compressor disengages by doing that, the CCU may have been keeping it engaged.
If it doesn't disengage, I would look towards the MAS controller.

On my 92, the signal continues from the pressure switch to the MAS Controller which is a glorified Solid-State Relay that, among other things, sends the voltage to the clutch on the compressor. I don't know it's location, but as I think about it, from my experience servicing other electronics, Solid State Relays usually go bad in the always-conducting state...

The only other thing that comes to mind is that the clutch could be mechanically frozen. That doesn't sound likely, though. You should be able to follow the wire from the clutch to a connector that you can unplug that would prevent the clutch from electronically engaging as a test.

My bet would be on your MAS Controller, but I don't see a listing for MAS diagnostics for the 97 model so I must presume that function has been moved to another device...

I hope my rambling has given you some ideas, to try, but again, it would be best that you start a new thread on this so as not to confuse the readers of this thread.

SPeace

__________________
02 S500
92 500SL
92 400E (Sold)
87 300E (Sold)
83 300D Turbo (Sold)
75 300D (Sold)
74 240D (Sold after 20 years)