As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - CREW REPORTED ACRID ODOR IN COCKPIT AND CABIN. EMERGENCY DECLARED FLIGHT RETURNED DFW LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND LEFT AIR CYCLE MACHINE GRINDING. REPLACED LEFT ACM. SYSTEM GROUND CHECK NORMAL OPERATION.