As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT PACK LIGHT ILLUMINATED AFTER BLOCKOUT ( ON THE GROUND) AND PRIOR TO THE PACK SWITCH MOVED TO ON. RUN PACK ( TURNED ON ) AND ACCOMPLISHED QRH CHECKLIST, PACK LIGHT STILL ILUMINATED. RETURNED TO GATE FOR MAINTENANCE ACTION. GROUNDED - YES. PERFORMED PZTC BITE FOUND LEFT CONT "TCV THID PACK" FAULT.VERIFY PASSED IAW FIM 21-63 TASK 802.A/C OK FOR SERVICE. NO HISTORY 30 DAYS.SEAMC PAT NOTIFIED, GROUND VERIFICATION SECCESSFUL.