As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN PRESSING RECALL ON MASTER CAUTION ZONE TEMP LIGHT FOR CONTROL CABIN COMES ON. PER QRH WHEN MASTER CAUTION IS RESET LIGHT GOES OUT. REPLACED M324 AIR CONDITIONING ACCESSORY UNIT TESTED ACAU NORMAL REF MM 21 51 02 400 801. RAN BOTH PACKS FOR 20 MIN PERFORMED BITE ON BOTH CONTROLLER NO FAULT LOGGED.