Originally Posted by zeke

This is in the 240D (manual CC)

It sounds like a pigeon, and seems to be coming from behind the instrument cluster.
Like a whining gurgle? Kind of rhythmic, or maybe cyclic.

When I turn the compressor off it goes away.

Doesn't vary if I turn the compressor control knob up or down - if it is on, it makes the sound.

The speedo seems to dip slightly with each pigeon "coo".

A/C seems to be working, though maybe not quite as well. (It has been converted to 134a, so it isn't ever a freezer.

What should I look for?