I do have system voltage on the pump, I have tried disconnecting it and it seems to have no bearing on the problem.

On the duo valve 1 and 3 are at zero when calling for heat and all three at 13.5v when calling for cold which I think is correct. I cant tell for sure the temp of the individual hoses as they are too far down for my large hands to reach but there is definitely warmed air coming through into the cabin., moreso I would say on the drivers side.

I did have a new duo valve fitted but had the problem with that one also so have taken it out again.

Would it hurt if I clamped off the feed to the duo valve to manually block the flow? or could this damage something?

Keith