Being the vehicle is a Berlina [this also includes Calais], you will have Climate Control!
I had a similar issue with my 2002 VY Calais Climate Control,
the Air would not come out of the "DASH AND SIDE VENTS"
And for a few years, it was so annoying,
So I said, I am going to find this fault, even if I have to pull the Dash out!!!
Well persistence paid off !
and no I didn’t have to pull the dash out !
but
I did pull part of it apart.
Under the Clove box at the back, against the fire wall, [you will need to remove the under-dash cover]
There is a Vacuum Manifold Unit [aka: Vacuum Solenoid Pack], with vacuum solenoids are mounted onto a Circuit Board,
You will see with a few different coloured pipes connecting to the front of it,
[one comes from the Vacuum Tank, the others go to the HVAC actuators]
Images 1 & 2
They just pull off easily, and are of a maluable type plastic.
Remove the Solenoid Pack, [2 screws]
and you can easily open it up, and see the solenoids. [in the next comment]
Some how condensation/moister can leak/get in to it, and corrodes the tracks on the circuit board, so hence they can fail to operate.
I used a [digital] multi-meter and checked the continuity between each side of the solenoids to the connector at the end, by following
the tracks.
And found the return [negative] track on the dash vacuum solenoid was damaged,
so I got a piece [1 strand of 4 core phone wire - Black], and soldered in place from the solenoid to the connector plug,
I secured it to the back of the circuit board, with dab of silicon in a few spots,
and used the same route as the circuit board track.
And it hasn’t faulted since.
Hope the atachments helps.