As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 3389 - AFTER DEPARTING DTW, CREW COULD NOT COOL THE DUCT TEMPERATURE BELOW 45 DEGREES USING AUTO OR MANUAL MODE. AIRCRAFT RETURNED TO DTW. MAINTENANCE OPERATED MANUAL TEMPERATURE CONTROLS. SYSTEM, OPS CHECKS GOOD. AUTO TEMPERATURE CONTROL IS DEFERRED PER MEL 21-6-(0). (M)