It is possible that the radiator was clogged or partially blocked. One other possible reason could be that because the changeover valve wasn't working, the main cooling system was getting hotter than normal. The coolant that circulates to the heater matrix also acts to assist the main engine cooling. I noticed that whilst my interior heating wasn't working, due to the bust changeover valve, that my main radiator cooling fan was coming on a lot more than previously. Going for a good run out this morning, so will update with any news once I get home later today.

Exactly.
I was surprised how cold those hoses can be... 2010 3.6tdv8 180k km.
sold 06 td6 160k
Sold 03 td6 260k

Hi

Sorry to bring back this post but I think I've got this same problem with my 4.4Tdv8 as I only get hot air when I chose full heat on the temperature selector (maximum temperature)

Could it be that when the car is running and you select max temp the car switches on the Fuel Burning and that is why I only get hot air when the temperature wheel selector is to max?

If this sounds possible it could solve my problem

In the other hand I`ve seen this changeover valve in AliExpress could you confirm that it is the right one to get?

Thank you

The FBH will only start or run when the temperature is 5 degrees or lower. It is possible that this valve is faulty, but there are also 2 other valves on the heating system which channel hot water from the engine to the heater matrices for driver and passenger heating. It's possible that it's these valves that may be at fault.

Thank you for the feedback

I´ve been checking the workshop and I´ve found this an please let me know if my conclusion cloud be right

OPERATION

The FFBH system operates in two modes:
Parked heating, to heat the passenger compartment while the vehicle is parked with the engine off.
Additional heating, to boost heater performance while the engine is running.
The ATC module disables FFBH operation if battery voltage is too low, as determined from an ambient air temperature
dependent voltage map. Where fitted, the battery monitoring system can also disable FFBH operation based on the
battery charge state with the engine off.
During FFBH operation, with or without the engine running, the coolant valves of the climate control system remain
de-energized and heater core temperature is directly related to the temperature of the coolant coming from the FFBH unit.

Additional Heating

Additional heating reduces the heater warm-up time and is also used to maintain heater performance throughout the drive
cycle.
The ATC module activates the additional heating mode when the engine is running and the following conditions coexist:
The ambient temperature is less than 1 °C (34 °F) on petrol vehicles or 8 °C (41 °F) on diesel vehicles.
The engine coolant temperature is less than 75 °C (167 °F).
The heater coolant temperature is less than 70 °C (158 °F).
The heat demand is more then 75%.
The blower is on.
From que Operation point of view, the FFBH can work with the engine running and if we check under what cases the FFBH will work with a running engine, we can see that it says “The heat demand is more then 75%.”

Could we assume that that is why we don´t get any hot air from the car vents at least er set the temperature control switch to maximum heat?

My thought is that when we set the temp switch to maximum this makes the system to ask for more heat what makes the demand more that that 70% and the switches on the FFBH and that is why we only get heat setting the switch to max

That this make sense? 2012 Range Rover 4.4 tdv8 Autobiography

Just registered to add to this thread as it is the only one which really helped me fix my heating issues, when googling my problem.

I had no heat, fans worked and could be directed with controls. Periodically I would get a tiny bit of a temp change but never very much.

I had the heater control valve changed as it was a cheaper part and my reading made me think it would be that. However, whilst it did seem to allow for a slight temp i crease, it was nothing like correct.

Next move was to replace the changeover valve. I bought a pattern part from Amazon which was around £40. It took some mucking about to replace however, it turned out to be the offending part.

I have put some photos below to show where the part is and offer a touch of advice for the job

Remove cabin filter assembly. just 2 13mm bolts, 1 at either end, then pull assembly up and out.

Click image to enlarge

Click image to enlarge

Click image to enlarge

GReat info DeeBeeGee

I have to get this job done on my 4.4 Tdv8

Thank you 2012 Range Rover 4.4 tdv8 Autobiography

Thank you for the clear instructions DeeBee, much appreciated !