water pump
Effectively all the fuel that it burns while idling. You are getting 0 miles per gallon while idling.
Low coolant, failed thermostat, partially plugged heater core...............
The #1 cause of cold air from the heater when the car is stopped, or the engine is idling, low engine coolant levels.
There are two hoses that go to the heater core, when the coolant is flushed an air pocket forms preventing hot coolant from reaching heater core while at idle. Happened with all our police impalas. Tell the dealer to fix it.
May have an answer already, but be sure that the radiator is full of coolant.
Could be low on coolant, a stuck open thermostat or a partially blocked heater core.
BAd radiator cap, low coolant or (leaking), Bad thermostat, cooling fans not turning on.
Poor circulation through the heater core. Probably a semi-plugged heater core or a faulty thermostat (assuming the coolant level is full).
No, I would suspect a stuck open thermostat, a failing (worn) water pump or clogged heater core. Also chedk for a sticking heater control valve in the coolant circuit if fitted. It could also be a internally swelled heater hose from the block to the heater core blocking proper coolant flow..
Drain coolant, remove anti freeze plug from block (corresponding size to the size of your heater coil plug) and install this plug carefully, using a large nut and a hammer. Refill coolant, let engine idling warm up, check coolant again and the installed heater plug for leaks. Now you can insall the cables, away from any moving or hot parts.
If it blows warm while idling and cool as you accelerate down the road, the coolant is low and or doesn't have proper mixture for your avg. temperature.
Its prob the radiator fan. Or you are out of coolant.