As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT PACK VARIES 38 45 PSI RIGHT PACK APPROXIMATELY 23 PSI OBSERVED AT FLT LVL 38000 PER FLT CREW. PRECOOLER CONT VALVE FAILED HEALTH CHECK. REPLACED PRECOOLER CONT VALVE REF MM 36 12 02 400 801. INSTALLATION TEST PASSED. PERFORMED ENGINE BLEED AIR CROSSOVER OPS TEST PER MM 36 11 00 710 801. L & R DUCT PRESSURE EQUAL & STABLE AT 41 PSI AT HIGH POWER. OPS CHECK GOOD.