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Q: Broken heater

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When running my heat it comes out cool/Luke warm. My coolant levels are where they should be and I've even tried to release air pockets within the system nothing is working. My car gets to operating temperature just fine and both the in and out hose on the heater core get hot. I've considered a flush but since both hoses are warm I assumed there wasn't any blockage. Any advice? SOS it's getting cold outside

My car has 140000 miles.
My car has an automatic transmission.

If everything in the cooling system has been eliminated as a cause - coolant level, flow, thermostat operating properly, etc., the issue may lie with the heater controls inside the vehicle. Within the "heater box" under the dash is located the heater core and air conditioning evaporator. The blend door is responsible for diverting the air flow between the evaporator for cold air and the heater core for hot air. If the blend door is not moving properly to divert air through the heater core to get hot, then you can still be getting a mix of cool air albeit cooled air if the A/C is on, or simply outside air. Possible causes for the blend door not moving properly can range from the hinge mechanism itself binding or broken, or the cable and/or electrical signal to actuate the door being at fault. Have a certified technician inspect the heating system to locate the cause.

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