As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SAME SQUEAL NOISE IN FWD CABIN AT CRUISE. PRESSURIZED CABIN WITH CEILING PANELS DOWN, NO LEAKS NOTED. TURNED ON CHILLER AND STARTED CHECKING CART VALVES AND FOUND ONE CART VALVE ACCORDION SEAL MISSING FROM CHILLER INLET TO CARD MAKING NORMAL HIGH PITCH SOUND. REPLACED ACCORDION SEAL.