2008 Mini Cooper S (R56) A/C compressor won't run

I’ve been in the process of putting my 2008 R56 Mini back together after replacing the timing chain, vacuum pump, turbo oil lines, and oil filter housing gaskets. If you’ve worked on one of these you know you have to basically take the front of the car apart to get access to the exhaust manifold so that you can get to the oil line and oil filter housing behind it.

Well all that "hard" stuff is finished and I’m now putting it back together. I can’t, however, get the A/C compressor to turn on. I did not originally open the A/C system and so that was intact. I later determined that the A/C compressor clutch was an open circuit and so I purchased and installed a used compressor. I did check that the clutch was good on that one before installing.

I also replaced the A/C pressure switch which is back near the firewall as well as the A/C compressor relay in the passenger footwell.

I’ve added the correct amount of R134a but it still does not engage. I’m out of ideas at this point.

Can anyone here give me anything else to check?