Yann it sounds like the speaker in the sid has failed . It is attached (soldered) to the PCB within the SID unit .
A cheap fix that I have used in the past it to connect a small speaker ( eg as found in older computers ) .
Done by soldering two fly leads to the pins of the original speaker . I have then double sided tape that speaker to the outside of the SID unit .
If you want a more professional ( original ) fix , then you can buy replacement speakers from SAAB SID AC unit LCD pixel failure unit repairs DIY - new ribbon cable.
They also offer a repair service if you are not confortable working with delicate soldering on a PCB .
Yann , WHat other sounds are you expecting ? It will give the blinker click , and also beep for certain faults or steps in a convertible roof operation, eg Finished closing . If you have the blinker sounding , I suspect the job is good !Yes, the little speaker on SID.