As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OUTPUT TEMP OF RT & LT PACKS ARE NOT THE SAME IN CRUISE FLIGHT. RIGHT PACK IS STABLE 22C. LEFT PACK VARIES FROM 0-10C IN A SLOW CYCLE. TRIM AIR ON. ACFT GROUNDED. R & R LT PACK TEMP BULB T488 IAW WDM 21-61-51. LEFT PACK TEMP INDICATION NORMAL.