What was found
WHILE AT GATE PRIOR TO PUSHBACK, CREW NOTICED SMOKE/HAZE COMING FROM REAR OF THE CABIN NEAR LAVATORY WHICH BEGAN TO FILL THE CABIN. SHUTDOWN AIRCRAFT, & BEGAN TO ORDERLY DEPLANE. ARFF & EMS WERE REQUESTED. AIRCRAFT REMOVED FROM SERVICE. INSPECTED LAVATORY, NO DEFECTS NOTED. PERFORMED INSPECTION OF LAVATORY FIRE EXTINGUISHER IAW AMM 26-26-01. NO DEFECTS NOTED. PERFORMED PACK BURNOUT IAW AWA SUP 09-037E. ODOR NO LONGER PRESENT. DURING PACK BURNOUT, RH PACK WAS ERRATIC IN AUTO, OPERATED NORMAL IN MANUAL. R/R KSHG RELAY IAW AMM 21-01-10 REF W/C 5 FOR OPS CHECK REMOVED COCKPIT TEMP SENSOR IAW AMM 21-61-28 INSTALLED TEMP SENSOR PER AMM SUP 06-062