For those considering AC installation in their M939s, be aware that the alternator will need to be upgraded to a 100 amp or >unit. I've suffered multiple electrical system faults due to alternator not liking the additional load. So far I've replaced the ABS ECU, the fail safe module, and the alternator. I might also need to replace the PCB due to recent symptoms. I am currently in the process of acquiring a 200 amp alt to power my M923A2. Good luck to all.
The AC works flawlessly and cools well. However, after a 10 min drive, the 60 amp alternator goes in to an overvoltage condition which will/has damaged electrical components. My Hawker batts are in good shape, so alternator voltage dump doesn't seem to be the case.
Any electrical experts on here care to shine light on this issue?