Nissan Repair: Heater, heater core, stop leak

Question
Thank you for your response.
Do I have to take the dash apart to get to the firewall?  If not how do I access it?
Thank you!
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-----Question-----
My heater is running hot only when driving my Altima.  When I idle it goes cold.  How do I backflush the heater core gently?
Thank you for your time, it is greatly appreciated!
-----Answer-----
Cheri,

No real way to do it gently.  I would remove both hoses at the firewall and use a hose to backflush it.  But, no way to know if the heater core will survive.   Someone probably used stop leak in the past.  If you run the car and feel the heater hoses you can find which way the water flows.  The hotter hose is water going into the heater core.

Answer
Cheri,

The hoses are on the engine side of the firewall.  So, open the hood and look for the hoses that go into the firewall from the engine.  The should be easy to access and they are round as a quarter and black in color.  Look behind the engine since the hoses are between the engine and the firewall.