As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT ARRIVED TO MEX WITH APU AND HIGH PNEUMATIC PURGE OF LEFT AIR CONDITIONING OUT OF SERVICE AND DEFERRED, SO GPU WAS CONNECTED AND IT INDUCED SMOKE INTO THE CABIN WHEN BOTH AIR-CONDITIONING PACKAGES WERE CONNECTED. AIRCRAFT WAS SENT TO THE HANGAR TO TEST THE PNEUMATIC SYSTEM IN MODE 1 IAW MM 36-10-00, ADDITIONALLY THE APU WAS OPERATIONALLY TESTED IAW MPCM 49-00-01.