2011 heater core, no heat.

My 2011 4R has no heat. A shop claimed the core is plugged. Has anyone replaced a heater core or are there other things to consider, such as heater valve (if any) or ways to determine if it's actually plugged. My experience with other vehicles is that it's difficult to flush a plugged up core.

 

I'll throw in my experience with heater cores. I had a 97 blazer with a clogged heater core, no heat at all in the winter, everything else functioning.

I attached my garden hose, with hose clamps and a little piece of rubber and cranked it on. The other side of the core oozed thick black stuff and then pop! Clear clean water.

So I definitely know it's possible to clean them, at least on a 97 blazer haha

 

This...^^^

Disconnect both sides at the firewall, and hook one side up to a garden hose. If it cleans out, you are good to go. If not, replacement time,,,
Be careful if you use compressed air. Dont ask me how I know that.

 

Another thing to check would be the air mix servo that varies the temp between the heater core and ac evap core. If the servo is stuck in a certain position it will close off airflow through the heater core and make it seem like there is no heat. If you flush the core and it is ok that is the next thing I would check