I have a working theory on this while waiting to see if
@cheeters can add anything else.
At a PTO2 drive day I was told by an Ineos rep that the air conditioning system uses a engine coolant based heat exchanger instead of a standard condenser core in front of the radiator. I can't easily see a front mounted condenser so I went digging around. I think this (pic) is the A/C heat exchanger, mounted on the left/near side of the engine. It has A/C pressure lines and coolant hoses. The round canister could be the receiver dryer body. Can anyone confirm this is the A/C heat exchanger (condenser)?
Based on what
@cheeters shared above:
"An air-lock in ancillary system caused an overheating in an sensor causing the air con to be turned off and also the cooling fan to run."; an airlock in the coolant sub-circuit would degrade A/C operation because the gas temp on the outlet side would be high. The responsible computer would first try to compensate by running the cooling fan, but if that didn't resolve the overheat condition the A/C would probably be shut down to prioritise and protect engine cooling.
Eliminate the airlock and the operating temperature and A/C operation would return to normal.
Maybe...