Explorer 4WD V6-4.0L (2009)
Heater Core: Testing and Inspection
Heater Core - Plugged
Climate Control System
Component Tests
Heater Core - Plugged
1. Check to see that the engine coolant is at the correct level.
2. Start the engine and turn on the heater.
3. When the engine coolant reaches operating temperature, using a suitable temperature measuring device, check the heater core inlet and outlet hose
to see if they are hot.
If the inlet hose is not hot:
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the heater control valve may be stuck closed.
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the thermostat is not working correctly.
If the outlet hose is not hot:
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the heater core may have an air pocket.
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the heater core may be restricted or plugged.