Hi All
Had the same problem on my jtd, some things I noticed.
When on Hi although you get warm air from the screen vents the foot vents stay cold until the engine warms up.
On mine the fins on the drivers foot vents were deflecting the heat upwards under the dash( I think probably a dodgy batch of vents) there was no way you could turn them round or fit them the right way up, very strange, ended up cutting the fins out works O.K now.
I also noticed with the engine warmed up when you get heat only one side if you shut the engine down and restart, it usually cures it.
The other thing that seemed to improve things was with the self learn mode on the climate control.
I can’t remember if it’s ignition on or off but if you hold the temp select button in with the manual/auto button for a few seconds you will hear the flaps running through various sequences then stop that’s it. You will also get some numbers flash up on the display, not sure what they mean, no doubt someone will come along with a better explanation.
Good luck