What was found
DURING CRUISE FLIGHT, AT FL 340, CONTROL CABIN AUTO TEMP CONTROL DELIVERS NO HIGHER THAN 19 DEGEES IN THE MAN/OFF POSITION THE SYS DELIVERS 23 DEGREES CONSEQUENTLY, THE PF AND THE PNF ARE NOT HAPPY BECAUSE THE ARE COLD AND DISTRACTED. PASSENGER CABIN CONTROLS/ INDICATIONS NORMALLY OPERATING. ACFT GROUNDED. ACCOMPLISHED FIM TASK 21-61/861. PACK/ZONE TEMPERATURE BITE CHECK OK ON BOTH CONTROLLERS. REPLACED TRIM AIR PRESSURE REGULATING AND SHUTOFF VALVE (V 146). INSTALLATION TEST PASSES REF AMM 21-62-01/401 AND FIM 21-61/861 PARA K.(3). INSPECTED SENSE LINE AND HOSE ASSY OF PRSOV IN RT AIR CONDITIONING BAY, NO DISCREPANCIES NOTED.