As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT PACK LIGHT ILLUMINATED DURING DESCENT BELOW FL260 SINGLE PACK LIGHT STAYED ILLUMINATED. GROUNDED - YES. PERFORMED PZTC BITE - B737-900 AMM 21-61-00. FOUND #1 PZTC LOGGED LEFT PACK TCV. ONE TIME. ABLE TO CLEAR FAULT. GROUND RAN LEFT PACK FOR 1 HR. NO FAULTS LOGGED. SYS OPS NML. REF AMM 21-61-00/501.