As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AFTER TAKEOFF FROM DFW, BOTH PACKS FAILED AFTER REACHING 32,000 FEET. CREW ACCOMPLISHED AN EMERGENCY DESCENT AND THE CABIN ALTITUDE REACHED A MAX OF 13,000 FEET. THE CREW ELECTED TO RETURN TO DFW. EMERGENCY DECLARED AND AIRCRAFT LANDED OVERWEIGHT WITHOUT INCIDENT. MAINTENANCE FOUND HEAT EXCHANGES CLOGGED AND DIRTY ACCOMPLISHED WASHING OF BOTH PACK HEAT EXCHANGERS IAW EA376934 UP TO STEP 9.