The e-box fan is located on the passanger side. Humming noise when a/c is on comes clearly from drivers side.
Can someone tell me what is the secondary pump?
Thanks

hi,

Wasserschlauche/Wasserventil BMW X5 E70, X5 3.0d (M57N2) ? BMW Teilekatalog

number 1 ...
it is a pump which helps the cooling and heating system
i heard about changing the pump, or only the bracket that holds it....by some X5 owners was it a solution by other the same noise!!
i also have it, i am out of warranty...and do not want to spend money on a new pump which should work properly after 2 years ...instead it makes that annoyong noise i will hang myself if i hear it again...

i want to take it out with a friend to see exactly how it looks...
bye

***Update***
 

Just an update for this thread,
As stated in earlier posts, the faint hum comming from the climate control that drove me nuts for a while was the secondary pump.
Dealer replaced it at no cost, even though my car was out of warranty. :D

Ditto here. MY '10 35d. Faint hum - constant pitch and loudness when you turn on the fan. dealer replaced aux water pump. Problem fixed. Work order states:
1 64-11-9-197-085 ADDITIONAL WATER PUMP: 641030