As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT:4051 FLL/MHH LOUD POP HEARD BY FLIGHT ATTENDANT AND PASSENGERS SLIGHT SMELL OF SULFUR MOMENTARILY IN COCKPIT AT SAME TIME LOST ACM COOLING. RETURNED TO FLL LANDED WITHOUT INCIDENT. REPLACED RIGHT AIR CYCLE MACHINE OPERATIONAL AND LEAL CHECK GOOD.