Hi, hope someone can help...

My 2010 L322 4.4 TDV8 Climate Control isn't working as expected. In full auto mode, and set to 21 degrees on both sides, it seems to sometimes get to temperature, other times go too hot and make the cabin really stuffy. It seems to work better, if you set it to blow to feet, face and windscreen, or indeed if you alter the blower speed, but left on full auto, it's all over the place. I was under the impression you just set the temp and it keeps you at that temperature come rain or shine, but instead, I'm having to constantly change the settings. It is fully gassed.

There is a whistle that comes and goes from inside the dash in front of the driver as if something is in the vent stopping a flap opening or closing, but that doesn't feel like the whole cause.

Any ideas?

Sorry to raise an old thread. This is happening to mine.
Cabin warms up at the same rate as the engine but doesn't stop at the 22 degrees setting on the controls.
Tested the 2 temp sensors located behind the Hvac controls, they seemed fine, resistance dropped when they were warmed up.
Knew I had an old problem with the blower and had a new one on the bench so fitted it along with a new FSR.
Made a difference - the rear blower became on continuously! Had to remove the fuse for it.
Had replaced the heater control valves last year so got a rebuild kit for the old one. Fitted, no change.
On the motorway the rear heater became so hot I could barely touch the plastic around it. At the front the bolster next to my left leg also became unbearably hot.
Had some control at the front by turning temp down and fan to one light with the centre control wheel on blue. Then it would get too cold. The bolster followed the same pattern.
I think the heater control valve is working, perhaps not brilliantly, because I can cool down the front.
I'm very confused about the rear which seemed to happen when I was replacing the FSR. Is the wiring in that area related to the rear blower?
If the heater control valve sends coolant to each side, where does the rear get coolant from?
Can anyone tell me where the earth point (K108 I think) is located? It seems to be the earth for most of the units in the dash. Can't see it in the WM.
I'm suspecting the control unit. A couple of weeks ago I noticed the night lights surrounding the knobs etc weren't working. They are now. Also the switch to control the rear heating didn't light up. It does now.
Sorry for the essay. Any help much appreciated. 2007 3.6 TDV8
1979 Mini Special
1988 Yamaha FJ1200
!952 BSA Gold Flash