my 2008 TDV8 is also one those L322s which likes to drain battery with a little help of HVAC fan in control panel

I have changed "final stage resistor" with new but nothing changed - did a test by putting a little tissue paper over little grill on HVAC panel, left it overnight with doors locked and tissuepaper was still there in the morning - means that little fan inside HVAC control panel was working all night and sucking air

my genius idea is just putting a "XXX minutes delay relay" to cut-off voltage to fuse number 12 in glove box (which controls "Air conditioning, Heated seats - front") after ignition is off

I have read that, if I do that, the only thing will happen is loss of memory of HVAC panel's last configuration

but temperature control is manual!! so I will be leaving them in preset position always and after I turn on ignition in the morning the only thing I need to do is just pressing AUTO button or turning knob for fan level

point is, am I wrong with my genius idea or is it acceptable?

I imagine you are aware of this:
Fast forward to 6:20 and listen to what Harry says about the button:

https://www.youtube.com/watch?v=gl51reRXxgE

No idea how this works, but it sounds like it leaves the HVAC system on.

Mark

I havent mentioned about that PROG button - I am talking about middle knob when you press it and it auotmaticly adjusts fan spped and vent mode...

I wasn't trying to tell you which button you were talking about. I was merely pointing out one way the HVAC system may stay active.
Good luck.

got it - the best is to take action and try

If you want install this "XXX minutes delay relay", then why don't just connect it to the little fan behind the HVAC dash? No worries about losing settings.
Just my two cents

hvac panel is full of 2008 model technology elecrtronics and I didnt want to touch that piece - just want to shut off it