Heater problem

I have a 53plate facelift td4 freelander. The heater works fine and blows hot air when up to temp, but as soon as I stop driving, (stop at lights, traffic jams etc) the heater blows cold air. The other half has been driving the freebie since we got it 2mths ago, so I don't know if this has been the case from when we 1st got the car or it's a problem which has just started. Cheers for reading this post and I would be very greatful for any help.

this useful?

Yeh! but my heater goes really hot. Once the temp on my freebie is up to about half way and you put the heater on, then the air from the heater is really hot. It stay's like that untill you stop the car. No matter how far I drive or how much I play about with the heater controls, it stays hot. I can reduce the heat with no problems. It's only when I stop that I get problems. Keeping the engine running, wait about 2mins and I get cold air. Drive off again, ta-da! I get hot feet again. HELP!

thermostat ?

Could be a partial air lock.Plenty of water flow when engine/water pump is revving high,but sod all when ticking over .There is a bleed point on the flow to the heater matrix.

Well done Longdog. Hot feet again. Thanx