Cadillac Repair: 1987 Coupe Deville 4.1 engine 92,000mi. over all good condition., coolant leaks, combustion chambers

Question
Coolant temperature fan light(red) will flicker on and off,especially after car hasn't,at been run for a while. It will go off. AC is fine,not overheating,but radiator overflow bottle is usually dry. Radiator is full. Could the red light be just erratic? Why is the overflow bottle always empty. Do not see anti-freeze under car or in oil. Thanks very much.  Vince

Answer
If the overflow jug keeps going dry and you have NO external coolant leaks then your most common problem is faulty head gaskets that is allowing coolant into the combustion chambers.

There is also the possibility that the ENGINE METAL TEMPERATURE SWITCH is faulty on the engine and needs to be replaced.

It is located about 3 inches from the top of the oil dipstick tube and has a single spade connector wire attached to it. I would replace this FIRST.