What was found
AFTER E1 START, SMELLED A BURNT RUBBER SMELL & CABIN FILLED WITH A LIGHT WHITE HAZE. APU ON WITH PACK 2, NO PROBLEM, E1 ON PACK 2 WE BEGAN TO SMELL A BURNT SMELL & HAZE. TROUBLE SHOT & FOUND NR 2 PACK ACM LOCK UP. R & R NR 2 PACK ACM IAW AMM 21-51-03. OPERATIONS CHECKED GOOD. NO ODOR OR SMELL DETECTED AT THIS TIME.