You have a 1995 dodge Dakota sport when it is idling the heater blows warm air but when you start to move the heater starts to blow cold air?

Answer 1

Check the coolant level. You might just need a little extra anti-freeze. Thermostat may need replaced I just went through the same thing on my 98. If bleeding the air out of the system does not work try this. With the truck running check the temp of the coolant lines going to and from the heater core. (about 1-1/4" in diameter hoses that go to your firewall.) As you face the engine the left hose is the inlet hose and the right is the outlet hose. If the inlet hose is warm-hot to touch and the outlet hose is cool then you may have some blockage in the heater core. Now turn your heater fan off or to low speed and check the outlet hose again. If the temp is rising the you still have some flow through the core and may be able to flush the gunk out. I went to the hardware store and purchased a female garden hose replacement end that would fit a hose with a 5/8" ID. Take off the clamp that you would secure the hose with and just use the barb end to insert into your heater core hose. With the car off and the engine cool remove the right outlet hose from the waterpump. Then the left hose can be split at the union fitting that is about half ways to the heater core. Now you can try to flush the core. Insert the hose barb that you have purchased into the right outlet hose and move the left inlet hose away from the engine so that you don't spray water on the block or manifold. Turn the water on and flush the core. You will probably see some grey water come out of the inlet hose. Run till clear. Turn off the water. Remove the hose from the outlet hose and move to the inlet hose. Flush again with the water running in the opposite direction till the water is clear. I had to do this about 3 times till the core was clean. I did use hot water but I don't think that is a must. After you are done flushing replace the hoses and add coolant to the radiator till full. Start the engine and let it idle till the the thermostat opens. You should see the coolant rise and then fall in the radiator neck as the air is bleeding out of the system, replenish the coolant as it goes down. . While the system is bleeding you should be able to feel the outlet hose get warm. If it is you should have heat. Good luck and be careful.