Car will make when running even if heater core is not burned out.
First, be certain it actually is in your heater core. A heater core doesn't have any moving parts, so if there's a noise coming from it, then it's probably from physical damage or a puncture, and it'll have to be replaced.
yes.
Generally the coolant goes in the bottom of the heater core and out the top only because the coolant makes less noise this way if there happens to be trapped air in the system, otherwise it doesn't matter.
The heater core may be plugged or bad. You can either flush the heater core and the 2 lines running thru the firewall to the heater core or you can replace the heater core.
This is an indication that your heater core is leaking. To stop the leaking you will have to replace the heater core or stop using your heater.
Low coolant and air in the heater core.
Take both heater hoses off at the heater and the hose running from the front, attach it to the rear of the engine.
You may smell coolant when the ac is running but a leak in the heater core won't cause the ac not to work.
A very basic answer is: The hot water the engine produces is circulated thru the heater core. The heater core looks like the autos radiator only smaller. The heater core is located inside the heater box. So as the engines hot water circulates thru the heater core the heat will transfer into the heater box. As long as the engine is running and everything is working properly the heater core will stay hot inside the heater box.
Means that your heater core is leaking coolant. Has to be replaced.
Temperature control in dash by heater core is broke.
The heater core is still having hot fluid running through it. Check to insure that the shut off is stopping the flow through the heater core.