Hi . 2012 tdv8 4.4 . Hi recently changed the engine oil cooler and now have only cold air blowing from the heaters. How do I bleed the heater matrix ? Thank you

I would let the engine idle with the expansion cap off for a while.
Do you know there is a bleed screw on the expansion tank as well?

I'd follow the process described in the workshop manual (wiki section of the site) because, it details step by step what you should do to re-fill and bleed the system.

Yes, there is a bleed screw on the top radiator hose to the right of the expansion bottle. 2015 Range Rover Autobiography 4.4 SDV8