What was found
CABIN & COCKPIT FILLED WITH SMOKE AFTER APU STARTED NR 1 PACK AUTO FAIL DISPLAYED. DEFER COCKPIT TEMP CONTROL SYS IAW MEL 21-61-14. CAT C, MC ADVISED 96041. ENTERED INTO MMO2, PLACARD INSTALLED. INVESTIGATED CTRL 2481268-1 NR 1 LT AUTO PACK FAIL, SMOKE IN CABIN, DUE TO SEIZED LT ACM IAW AML 2481271-2. THIS CLEARS DTRL 2481268-1, PLACARD REMOVED FROM MMO2 MX CTRL NOTIFIED 53431.