What was found
AFTER THE LH ENGINE WAS STARTED, THERE WAS FUMES AND A LIGHT HAZE THROUGHOUT THE CABIN AND COCKPIT. THE PLANE WAS DEBOARDED AND NO MEDICAL ATTENTION WAS REQUIRED. THE FUMES AND SMOKE WENT AWAY AFTER THE ENGINES WERE SHUT DOWN. / REMOVED AND REPLACED ACM IAW CRJ 900 AMM 21-51-08-000/400-801-A01. ACM OPS CHECK GOOD. REMOVED AND REPLACED LH TEMPERATURE CONTROL VALVE IAW AMM 21-51-20-000/400-801-A01. OPS TESTED AND LEAK TESTED GOOD. NO FUME SMELL NOTED IN COCKPIT OR CABIN DURING OPERATION OFF OF EITHER BLEED SOURCE.