What was found
COCKPIT CABIN TEMP CONTROLLER WOULD NOT PROVIDE WARM AIR IN FULL WARM POSITION. COCKPIT REMAINED VERY COLD THROUGHOUT FLIGHT. ACFT GROUNDED. ACCOMPLISHED BITE CHECK OF BOTH PACK/ZONE TEMP CONTROLLERS. BOTH PASS AIRFLOW ACROSS CONTROL CABIN TEMP SENSOR OK. R & R TRIM AIR PRESSURE REGULATOR, TASK 21-62-01-400-801 POS 1-8. PERFORMED OPS AND LEAK CK, BOTH CHECKS WERE GOOD, IAW AMM 21-62-01-400-801, STEPS H-J.