As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT PACK LIGHT ILLUMINATED ONCE CRUISE ALTITUDE OF 330 REACHED. QRH COMPLIED WITH. LIGHT EXTINGUISHED HOWEVER PACK LIGHT ILLUMINATED AGAIN AFTER A FEW MINUTES. GROUNDED - YES. REPLACED LH PACK RAM AIR DOOR ACTUATOR WITH NEW REF B737-800 AMM 21-51-21.