bought a 98 sedan deville w/91k in fl, my wife is now, on her own, driveing the beauty back to michigan. seems after 15-25 miles the a.c stops beinging a/c and becomes a vent system with warm air. i have had the system checked out, no problems. so.. has anyone ever been hear before???whats the problem?dc

Enter the onboard diagnostics and see if there are any DTC's stored. Sounds like it is low on freon.