VR6Pete, Cheers for the reply, Rad fans do kick in etc, I had recently replaced the Thermostat, due to cool running, and that is now all sorted but just before that was done, noticed one morning that I had no heat from the heater, however this went away but has now returned and has been like it for the last week, suspect either there is a air bubble maybe? or there is some problem with the climate control, have been told that you can access the fault codes somehow?, I am not loosing water anywhere either? cheers.