My pick up heat is on an it goes to the middle of
the gauge an blows out heat than cools down an
blows cold air. It goes up an down hot, cold.
Check coolant level. Check water pump and radiator for flow. Replace thermostat (you can test old one for operation with a pan of boiling water and thermometer). You can also check heater core flow by removing heater hoses from engine and connecting to a hose. I don't know if yours has a heater valve or not, that would be a valve that opens to let coolant reach the heater core, the valve would be controlled by the climate switch, if it has one, check it too. Good luck.
Search Dodge Ram 1500 Questions
Dodge Ram 1500 Experts