...when turn AC off the light turns off....its a 87 cadillac deville...
turn on AC coolant temp light comes on on 1990 Cadillac DeVille
when you turn a/c on how long b4 the coolant temp light comes on?
..about ten minutes
have you ck'd your coolant level. maybe the car is starting to overheat or the a/c cooling fan is not working properly