As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF, CREW NOTED HOT BURNING SMELL IN ACFT, RET TO FIELD. INSPECTED AND GROUND RAN ACFT, NO BURNING SMELL OR DEFECT NOTED. INSPECTED FOR SECONDARY DAMAGE, NONE NOTED, SUSPECT ODOR FROM ACM PACK HOT CAUTION LIGHT AND NOISY ACM NOTED DURING TAXI IN ON PREVIOUS FLIGHT. ACM WAS MEL'D FOR THAT DISCREPANCY.