The heat will not come through the ducts until the engine revs above idle only cold air. I noticed the coolant was low so I filled to the line and it worked the heat comes on during idle. After 3 days it stops working during idle and I noticed the coolant level was low again. I see no white smoke from the exhaust and no spills under the engine. Please help

Have a mechanic pressure-test the cooling system to determine where the fluid is going.

Have a mechanic pressure-test the cooling system to determine where the fluid is going.

Good suggestion thanks Ill do that today