As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON GROUND WITH APU RUNNING, CABIN PAC OFF, CABIN FILLED WITH SMOKE. [SUP 05-03-07] TO FAILED CABIN PAC AIRCYLE MACHINE. WHILE T/S FOUND LP BLEED AIR ISULATION VALVE STICKING. REMOVED AND REPLACED ISOLATION VALVE AND CABIN AIR CYCLE MACHINE. BOTH OPS. CHECKED AND LEAK CHECKED GOOD. IAW. 750 M/M CH. 21-51-00.