What was found
FLIGHT DECK BECAME VERY COLD. LT PACK SHOWING 0 DEGREES. EMER PROC PERFORMED.CREW DEBREIF. CREW REPORTS SEVERSLMHOURS AT CRUISE NOTICED FLT DECK GETTING COLDER, ATTEMPTED TO INCREASE TEMP THROUGHNTEMP CONTROL DIALS WITH NO CHANGE. FOLLOWED QRH DIRECTION TO CHECK TEMP OUTPUT & FOUND LT PACK TEMP READING 0 & RT PACK IN MID 20'S. TURNED LT PACK OFF & FOUND TEMP STABILIZED BUT NOT INCREASING. DURING DECEMT AT APROX FL19000 PILOTS REPORT SMEELING HEAT & THEN TEMP RAPIDLY INCREASED WITH LT PACK STILL OFF. CREW DEBRIFF CONT. CREW REPORTED THAT CABIN TEMP FOR PASSENGERS STAYED COMFORTABLE BUT WAS BEGINNING TO DECLINE WITH JUST RIGHT PACK. DUCT PRESSURE WAS CONSTANT & ADIQUITE WHOLE TIME. PREFORMED AIR CONDITIONING IBIT WITH FLOW SENSOR TEST, FOUND MESSAGE 21-55060 FLOW SENSOR OUT OF RANGE REMOVED NR 1 ENG FAMV IAW AMM 36-12-03-000-801. REQ INSP FOR KISS SEAL STEP G(1) OF AMM 36-12-03-400-801. COMPLIED CDCCL STEP G 1(A), (B) IAW AMM 36-12-03-400-801.ENG1 KISS SEAL GOOD.CLEAR TO CONTINUE. REF. GMM. 09-10-05 INSTALLED NR 1 ENG FAMV IAW AMM 36-12-03-400-801 UP TO STEP 3(I). DUE TO ABOVE FAULT MESSAGE REPLACED FLOW CONTROOPERATED AS REQUIRED. GOOD TO CONTINUE. NO ISSUES NOTED.