Ok, I would like to revive this thread with an update to the howling AC issue:

I took my car to the dealer last week to have the driver side window motor and controller replaced (window had stopped working, luckily in closed position), which fixed the window problem. Also picked up euro parcel shelf and aux input adapter.

I discussed the A/C howling noise with the dealer mechanics. We went for a test drive, and I was able to point out the howling noise to the mechanic. He heard it. However, it was not as pronounced as it is at times, and the engine vibrations that went along with it were also not nearly as pronounced. Back at the dealer, they hooked it up to diagnostics but predictably came up with nothing, so nothing was done and the howling continues.

I did a few more checks myself upon return home:
as Bartnik had suggested in another howling post, I listened for the fan noise when idling:
Idling the engine in the garage and engaging Ac does this, in this sequence:
AC is engaged, and engine note changes slightly. Cold air starts blowing.
About 30 seconds later, the engine cooling fan comes on.
About another 30 seconds later, either the fan goes into a high speed mode, or a second fan comes on, I can't tell which. At that time the engine rpm goes up from initial idle rpm of about 800 to 850 rpm, to around 1100 to 1150 rpm, and the engine vibrations now go up dramatically. You can tell the engine vibrations by just looking at the engine: when looking at the engine in this state, it is vibrating in a very pronounced way. When I then turn off the AC compressor, the rpm still stays high, but the fan noise goes down and the engine vibrations go back to normal.
I think there is a definite problem here, but I don't know what it is. I don't think some of the solutions posted on MINI2 are correct, I don't think it is related to the PS fan or one of the AC hoses.
It could be a problem with the AC compressor. Mine at least works fine in that it produces plenty of cold air, no complaint there.
I am puzzled by the number of fans associated with AC:
based on what I have been able to read up on, there may be three fans involved: the main engine cooling fan. Then, I have the impression that the MINI has a second air cooling fan for the primary radiator, that only comes on when the engine is very hot, or maybe it is the main fan that runs at two speeds? Then, there appears to be another fan that may kick in to cool the AC compressor? This is based in part on the number of fuses in the car that have a snowflake on them (three in total), and the fan noises, as well as what I have read elsewhere.

The howling noise incidentally can be replicated in the garage, for those of you who want to take their cars to the dealer for a howling demo: while the car is sitting there, if you rev to about 3.2 k rpm, the car will howl if AC is engaged, it will then stop holwing if you disengage AC. The holwing may be more pronounced if the car is hot.

What worries me more than the howling are the intense vibrations that come with it.

Markus

 

is there any new info on this? I think I've got the same problem in an '05.

Thanks!

 

And here all along I thought my MC had a rotary engine and the sound was perfectly normal...I just couldn't figure out why the engine only became a rotary with the air on

 

Just noticed my is doing the same...argh....

 

Same here!! Very annoying.

 

I forgot to take the clothespin off my nose, and now my wife is looking at me funny, not to mention the can of peas I dumped into a bowl. This place is getting me in trouble!


regards,
Red