Heater core

2013 RAM 1500
145,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC
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TIGER190#
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  • 1 POST
I've been told my heater core needs replaced, but there were not diagnostic tests done (at least not computer/machine based). Here is what is happening:
* When outside temp drops to 30s or below, cab does not get warm and blower becomes very insufficient.
* If it's in the 40s or above, hot air comes out, but does not blow hard out of vents or defrost. A/C works perfectly and blower runs at full capacity.
* We don't go through any coolant, do not smell coolant, and do not have the fine mist of coolant in the cab.

Thanks for any help, and please let me know if I can clarrify.
Oct 15, 2019 at 7:07 AM
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ASEMASTER6371
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Good morning,

There are no computer tests for a bad heater core. That is mechanical.

https://www.2carpros.com/articles/car-heater-not-working

Tests can be done for the blend door actuator for the heat and the temperature of the coolant in the cooling system.

The thermostat needs to keep the coolant at 195-200 degrees. The hoses going to the core must be that temperature at normal operating conditions.

It is possible the core is clogged with debris not allowing heat to come out. I would start by removing the hoses and running a garden hose through the core. Flush it both ways until it is clear and no debris comes out. It should flow equally when flushing from both sides.

https://www.2carpros.com/articles/replace-heater-core

Roy

Oct 15, 2019 at 7:22 AM