1993 Cadillac Sedan Deville: No Heat

Check and test the thermostat -check the heater core if its clogged and air blend door in heat poition

Feel the radiator and heater hoses after the engine has had time to warm up. They should all be too hot to hold onto for very long. If none are hot, replace the thermostat. If only the two small heater hoses are cool, back-flush the heater core with a garden hose. If all the hoses are hot, suspect a problem with the computer-controlled heater controls. GM has a ton of trouble with everything they hang an unnecessary computer onto.

Caradiodoc