heater temperature cold

Hi there, Ive just bought a Range Rover l322 4.4 V8 and the heater doesn't work.
The blower fan works fine and can be operated either by the auto switch or manually turned up and down however the temperature of the air doesn't get even slightly warm. The temp gauge reads temp normal with no fluctuation and there are no water leaks.
iVe checked the heater matrix pipes and they are cold. There is no heat in the pipes to or from the two blend valves on the inner wing. There is heat in the pipe up to the valve right at the back of the engine but no heat in the pipe on the other side going towards the blend valves.
There is some great info on this site but I don't seem to find this fault and fix. If I've missed it many apologies.
I suspect the valve at the back of the engine or a interior temperature sensor (wherever that is located). Can anyone help where it be a common fault or how to test and diagnose.
Advice much appreciated as its getting cold out there!

Has some one blocked off the heater pipes as there was a matrix leak?

Hi, thanks for the response, I did consider that but it doesn't look like the pipes have been disturbed at all. It does appear that either the valve is closed and stuck closed or the valve is being "told" not to open. I'd like to try and find out where the interior temp sensor is. I've now changed the two blend valves on the inner wing so it's not them.......the search continues

Sorted it. It was the valve right at the back of the engine. Replaced with a second hand unit for £25 and it works fine.