What was found
FLT 4378 - ORD - STRANGE NAUSEATING SMELL IN CABIN, SMELL SIMILAR TO OIL OR GAS. RAI CEILING LIGHT BALLAST, ROW 9 LEFT, IAW CRJ 700 AMM 33-21-03 AND RAI CEILING LIGHT BULBS 9 AB, IAW CRJ 700 AMM 33-21-01. PERFORMED GROUND RUN WITH APU AND NR 1 PACK FOR 2 PLUS HOURS. NO DEFECTS NOTED. OPS CHECK GOOD. RETURNED AIRCRAFT TO SERVICE. (M)