My 2006 Range Rover sport has an issue with heat out the driver’s footwell vent. In my case it is an actuator calibration issue. I unscrewed the actuator, left it plugged in, and manually flipped the blend door, with the fan on with at least three lights showing, the door will stay put. Heat flows. Turn the fan off and the door flips back and cold air comes out. I do get a blend door fault.

A local cal shop looked at it. They told me that it was a bad actuator, not the case. Actuator works fine, it just moves out of sinc with the requirements of the blend door itself.

You might try unscrewing the lower actuator on the driver’s side, plug it I snd move the dash Hvac controls. See if the actuator moves. Try manually flipping the blend door, there is a tab that the actuator mates to it’s that is accessible with the actuator disconnected.

It it is a pain to access but much easier to get to than pulling the heater core.

Phil