Re: XF Heater probs
Sorry - should have read in more detail! The heater tap is a small vacuum valve operated by a cam on the heater box, but if you have removed the the one in the engine bay it would make no difference.
so with this in mind, since there is plenty of coolant flow, I reckon the heater blend flap in the heater box is jammed closed. This is a vacuum operated flap, so if you have disconnected or leaky vacuum hoses/fittings, that would be your problem! No airflow through the core = no heat.
Hope this helps!