What was found
CABIN IS VERY COLD AROUND ROWS 6, 7, 8. UNABLE TO WARM IT WITH TEMPERATURE CONTROLLERS. GROUNDED - YES. CLEANED FILTER ON FWD CABIN TEMP SENSOR. USED APU FOR FUNCTIONAL CHECK OF HEAT/ COOL RHEOSTATS. OPS CK GOOD. OK FOR SERVICE. REF AMM 21-61-10. GOOD HEAT DISTRIBUTION THROUGHOUT ROWS 6, 7, 8.