My daughter's 405 had a problem with the temperature control not working. I could hear something whirring and determined it was the blend servo (that is the name in Range Rovers).
I pulled the servo out and found it was almost identical to the ones in my
1995 HSE Rangie on which I'd already replaced the blend flap servos and distribution flap servo.I pulled the 405 servo apart and found it had stripped gears. So I pulled a Rangie servo apart, found the gear ratios and feedback pot were the same so fitted the gears from it the 405 unit. (The Rangie gears are stronger). Fixed! And the temp control works again.
Something to keep in mind if your 405 temp control fails.
Ron Beckett Emu Plains, Australia