I have a '96 Devil and the AC control will not switch form "ECON" to "AUTO", so the AC pump never comes on. When I push the "AUTO/ECON" button, the LED shows it switching to AUTO, but as soon as I let go of the button it goes back to ECON. One day it was working fine, and then suddenly it didn't, so I am thinking it is an electrical issue. I checked the refirgerant level and it is good. Fuses in the fuse box are good. I replaced the AC relay in the fuse box just to be sure. So all the easy fixes have been tried.

** Update on the problem**
I disconnected the battery for a few minutes, to reset the computer, and the A/C worked normally for about an hour, then the problem returned.

What could be causing this????

hmm..if disconnecting it made it go away for a bit, it must be some sort of computerized issue. I am afraid that your situation is beyond my realm of knowledge of AC issues. have you spoken with a caddy dealership, or an AC specialty place? this may be a common issue.