I have a 1992 Dodge Caravan and I have no heat. It does not loose anti-freeze and has no leaks. It does not over heat or run any different than normal. Could it be a thermostat ?
I check the coolant levels in the radiator and over flow to confirm the customers story. I have found that sometimes a customer does not check the radiator and think if the over flow tank is full then the radiator must be full, this is not always the case. But after checking I found both to be full. I ran the engine to normal operating temperature. I then check the temperature of the upper and lower radiator hoses to make sure the thermostat was opening and circulating. And it was. At this point I checked to make sure both heater hoses were hot to eliminate the idea of a clogged heater core. It checked out OK. I then checked the only thing left. The flapper valve for hot and cold. Found the cable broken between the flapper valve and the control head. Customer did not want to spend the money for the repair and chose to have the flapper set to hot manually and left there as the A/C did not work anyway. Customer Happy!