Peugeot 406 a/c blowing continuously - noisy

Not so much,
And this is just guessing as to be accurate I'd need the RPO number of the sticker.
But as the blower is in part run by the BSI best idea would be to unplug the blower motor at the motor.
Or fit a S/H motor.

Thank you so much for your possible solution to the a/c problem . May I ask what the PRO number is and where can I find it in the engine??

RPO number is on a white sticker on the passengers "A" pillar,
just above the door hinge.
It's the bare minimum information needed to access a Peugeot wiring diagram.
Normal is the first 4 digits.
Though being French I've found the RPO on under bonnet strut tops and other placed than where it's meant to be.

Thanks for that - I will search for the white sticker (or grey by now) sticker in the morning.
Thanks again.