I've only had my van a few months, but mine always does a buzzing noise when I open the door. Its not as if its a buzzer per se, but does sound like something priming.
I've tried to do a video this morning but I couldnt hear it on the video. But I'll try again tomorrow.
Happens when opening any of the doors., Appears to be under the bonnet.
Now I've read this thread I'll take more notice of it and try and find the source. I just thought it was normal, Everything operates as it should.
Cheers Ali