I've the exact same thing. With air con on and engine at idle, very
noticable rattle from engine bay area. It has alwys done this (5 years
old now!) In the meantime the pump has been replaced for a different
problem, and rattle remains. VW couldn't find anything wrong! I believe
it is just something else slightly loose and when the aircon is on, due
to the slighly more load on the engine is alows whatever it is rattling
to do its ting. Increase the revs and it goes away.!
noticable rattle from engine bay area. It has alwys done this (5 years
old now!) In the meantime the pump has been replaced for a different
problem, and rattle remains. VW couldn't find anything wrong! I believe
it is just something else slightly loose and when the aircon is on, due
to the slighly more load on the engine is alows whatever it is rattling
to do its ting. Increase the revs and it goes away.!