I have heat only when fan is on low and i changed the acuator for flap and still no heat.it dont leak or over heat.
The heater core is always "on," in that there is always engine coolant flowing through it just like your radiator. If you have heat at low, you should have heat at every other setting. The temperature blend door directs incoming air to either pass over the heater core or to pass over the AC coil. I would check that the temp blend door is indeed functioning, and that the heater core is indeed getting fully hot (in other words no restrictions, blockages)
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