Heater Core " Plugged
WARNING: The heater core inlet hose will become too hot to handle if the system is working correctly.
Check to see that the engine coolant is at the correct level.
Start the engine and turn on the heater.
When the engine coolant reaches operating temperature, feel the heater core inlet and outlet hose to see if they are hot.
If the inlet hose is not hot:
the thermostat is not working correctly.
If the outlet hose is not hot:
the heater core may have an air pocket.
The heater core may be restricted or plugged.
If both are hot, the temperature blend door in the heater plenum may be broken or stuck.
You might also try a core backflush. Buy a flush kit, install the Tee in the return line(to pump), and disconnect the suppy hose, now backflush until water runs clear, I usually get two Tees, and flush both ways, a heater core is not linear, water path is much like a honeycomb. Hard to flush, radiator repiar shops use a pressure gun to clear them, and this codts about 100.00, but can save the time involved in replacing harder installations. If your core is easily accessible, changing it is the BEST answer!
Friday, November 27th, 2009 AT 7:45 AM