Many thanks for your answer.

FYI, after starting the engine with the A/C on MAX, the is no air coming from the front upper vents during 1 to 5 minutes but I can hear the fan spinning. Then after 1 to 5 minutes, the A/C is working normally. I have this problem only with the front vents.

My X5 is a 2002 4.4i model

Thank you in advance for your help