First off, I am posting this because I followed roughly 20 dying threads that never solved the issue.

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Today I actually got it. It is my duty to share…

Background: PO sold me 2011 R56 with 50k miles. Said air likely just “needed recharge.” Before I could get to that AC issue it developed a leak (classic drips forming on tranny) and I found myself replacing the thermostat housing. That all went well but I was a little leery as I was unable to get the cooling fan to kick on. When I unplugged the coolant temp sensor the fan did kick on though, so I knew the fan worked. A hotter day came along and the fan kicked in auto and so I thought nothing of it and considered it fixed.

On to the next issue, AC warm / clutch won’t engage. Ac gages hooked up showed equal psi on low and high side ~70psi. The engine rpm would increase but no clutch engage. I manually probed 12v to clutch and got the click I expected so all good there. Freon charge good, bought a Creator obd reader and confirmed there was high pressure readings and evap temps that all made sense (other posts had listed the “conditions for the compressor to engage”)

next I probed the white wire in the footwell harness that feeds the compressor clutch. Even though I could hear the ac relay click after snowflake button, still no voltage. Super confused at this point.

The odd cooling fan behavior from earlier comes back into my mind and I search a bit more. I see a user that had AC start working again after a dealer replacing his relay so for 30 bucks at Oreily’s why not. (Part number 25-0428) My mini only has the stage one relay so that’s what I was replacing. Pop it in when I get home and whooosh the cooling fan started up. Cool! But still no compressor. Probe for power at white wire in foot well and now it was hot! Now I was excited! Get under the car to start probing the wire closer to the harness and boy did I get lucky cause the corroded wire failed and snapped right then at a zip tie along the front bumper.

I stripped the wire and did a quick patch job with alligator clips, and click, whirrrrr AACcc.

Tldr: the cooling fan relay can prevent the ac clutch from engaging.