I'm thinking bad ground somewhere under the dash. Do you have any schematics for the car? They might be helpful, but even without them, you can inspect the wiring harnesses under the dash.1. DIC dead.
2. Cruse control stopped working.
3. HVAC has a mind of its own - recirc, A/C buttons do nothing but it'll randomly switch from recirc to fresh and run the AC so I pulled the fuse that allows the A/C pump to run because it would engage the pump when the HVAC fan was off.
Start at one of the failing units, such as the HVAC controls, and trace the harness back from it looking for a connection to ground. I'm guessing a ground wire broke loose from its eye terminal, and that is causing the DIC and cruise failures, and wonky HVAC.