As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: PILOT REPORTS AT CRUISE, R PACK RESET SW INOP & PACK OFF CAME ON. QRH PROCEDURE FOLLOWED AND RESET, HOWEVER LIGHTS CAME ON AGAIN - 10 MIN LATER. PACK TURNED OFF AND DESCENT FROM FL380 TO FL320 ALLOWED L PACK TO HANDLE PRESSURIZATION AND TEMPERATURE. MAINTENANCE REMOVED & REPLACED LOW LIMIT VALVE IAW AMM 21-51-11. OPS CHECK NORMAL.