Weird humming noise from front fender

[snakeyybro]

Hello. I bought E60 LCI 530xD a month ago. I did 2k km on it already and my issue started only few days ago. When i unlock the car something is starting making weird noise from front driver fender behind the wheel. Its like pump, ventilation noise, or maybe similar noise to WEBASTO running ( ye I have webasto in that car ). Sometimes it will stop making noise after 30 mins but sometimes its running for like 2 hours (locking car wont stop it either). I searched for that issue on many forums or on google but i didnt find anything useful. That sound is driving me crazy cause its very disturbing. Especially in night when i come home and it sounds like engine fan. But its not. Can you help me with that issue what it could be ? I tried to turn on and off webasto through iDrive or Remote Control but without result. The only thing i can think of is that webasto has some issue and it will automatically start when i unlock the car and after some time it will go to sleep. Thanks for any info or help.