Citroen C5 X7 no heating

[quzio]

Hello everyone, My Citren C5 X7 2.0 HDI hasn't had any heat for a while now.
The water pump, thermostat, radiator, and heater core have been replaced.
The system has been flushed several times.
The cooling system has been bled through the valves.
I noticed that the pipe going to the new heater core is hot, while the pipe leaving it is cold.
What could be wrong?

[Peter.N.]

Sounds as though the heater core is blocked but highly unlikely if its new. You haven't got the flow and return swapped over have you? I can't remember if that is actually possible. The lower pipe should be hot if they are the right way round. You could possibly have air trapped in the heater core, try disconnecting the return pipe at the heater with the engine ticking over and see if any air comes out.

Peter

[quzio]

Swapping the heater wires causes the opposite, one wire is still hot and the other cold.