I have a 2010 1.9 diesel SE automatic and have been having heater problems for some time now. Passengers side footwell and windscreen vents temperature working OK but drivers side only luke warm. No problems with thermostat or water pump , reaches 90 degs (normal) and does not use any water.Any ideas please.

Assuming you have climatronic unit there is the called flaps calibration - it may help in any case some have possibly stacked.

You can try.

With just ignition on, hold down the econ button and bottom left button of the 4 (front facing vent control) both simultaneously should display FR in small letters below a fan shape symbol, this resets the flaps, but often enough the motors themselves for the flaps fail from what I heard. This for the dual climate control version.

 

 

There's a possibility you might have a bit of a pig of a job because it's on the driver's side, but that's only what I'm told so it might be as simple a job as I had. Hope it helps.