I bought a new to me (justa) Mini R56 (non-s) last weekend. It had just under 100,000 miles and I got a pretty good deal on it. I just can't believe how fun it can be driving it.
Now that I've been driving it a week I've noticed an odd issue with the A/C... it blows cool air great. Then after driving for say 20 minutes or so, it seems to blow less cool air (it's still cool, but not as cold) and seems to release a sweet smell into the cabin air at about the same time.
I get the sweet air smell as well. As for the loss of cold air you may want to check your coolant level. The AC is disabled if the car cannot cool itself properly. I speak from personal experience and research on this site.
Go to the dealership when the service area is about to close and you might be able to get a free jug of coolant, at least that's what happened to me! At the same time the head technician showed me around one of the MINIs they had in the service bay, he said the owner has paid the dealer tens of thousands of dollars to do all of the mods (and there were a ton of mods, I think at the time it was getting a new JCW turbo installed into the S motor). And this head tech is the only person that is allowed to work on it! Supposedly one of the most powerful MINIs in the US.
It's always a good idea to check coolant level. If the AC is having problems, it might also be low refrigerant.
Look at the simplest causes first and you'll usually find the issue. I agree is also sounds as if you may have a coolant leak, as that's usually the cause of the smell.
Thanks for the tip bj, I hadn't thought about asking for a system check... ultimately that's what I remembered too... it's been ages since I've had a leak on any car... The car has a 3,000 mile warranty... I'll have to look into what it covers.
Today did a bit of experiment... I decided not to turn on the recirculation and no sweet smell... but the air didn't get as cool either... I believe I probably do have a leak, but am still not seeing drips in the drive way (argh)...
There is potential for low refrigerant (leak 1) and a cooling system leak (2). The thermostat housing in this car is a frequent failure point. The thermostat is cast into the housing and is a single unit to replace. Pressure testing the cooling system should reveal any leak.
Ok, I've played around with the controls and figured out part of it...
It seems to only leak when I set the A/C to recirculate from monitoring coolant levels, but I still haven't identified where it's leaking from... Does this make sense? Can someone explain why it would do it only when recirculate is activated?
Ok, took the MINI into a local AC guru who found zero signs of any leak, but pressure tested as requested anyway... still zero signs of leakages...
Since I have no knowledge of the history of the car, the tec added some dye to assist in finding it if it continues.
he didn't find an a/c leak ... this is good .... but you have some coolant someplace it should not be ...
could be residual from an old problem. Have you checked the cabin filter?
or, you could have a very small coolant leak where the drip or spray is cooking off before it can pool anywhere ..... I'd put clean cardboard under the car where you park and watch for drips . . .
I' haven't replaced the cabin air filter can't find one locally, but have ordered one. That cardboard trick seems like a good one... I'll probably park it in the garage tonight to verify it.
Sweet smell is a coolant leak. 
