As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMBOUT, LEFT DUCT PRESSURE WAS AT 20PSI AND FLUCTUATED +15PSI. RIGHT DUCT PRESSURE WAS STEADY AT 45PSI. ONCE LEVEL AT FL 370, BOTH DUCT PRESSURE STABLE AT 40PSI. ACFT GROUNDED. REMOVED AND REPLACED THE NR 1 ENGINE PRE-COOLER CONTROL VALVE IAW AMM 36-12-02-000-801/36-12-02-400-801 AND HIGH STAGE VALVE IAW AMM 36-11-06-000-801/36-11-06-400-801.