As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT RETURNED TO PLATFORM DUE TO DURING TAXING, THE DUCT OVER HEAT LIGHT TURNED ON. DURING MX REVISION, THE AIR CYCLE MACHINE IN THE LT AIR CONDITIONED PACK WAS DETECTED WITHOUT TEMPERATURE CONTROL IN MANUAL & AUTOMATIC MODE, SO THE LT AIR CONDITIONED PACK WAS DEFERRED IAW MEL 21-1-1A CAT C.. DURING OVERNIGHT CHECK, THE AIR MIX VLV WAS REPLACED IAW AMM 21-61-02, TESTED CORRECT & THE REPORT WAS CLOSED.