What was found
AT CRUISING ALT CREW NOTICED A BRIGHT LIGHT AND ARCING IN THE LEFT WINDSHIELD THAT LEFT A BURNT MARK IN THE WINDSHIELD. SHORTLY AFTER THE WINDSHIELD CRACKED AND THE CREW FOLLOWED THE QRH AND RETURNED TO CLT. A/C DID NOT LAND OVERWEIGHT UPON RETURN. L WINDOW CRACKED IN FLIGHT. REMOVED AND REPLACED LH WINDOW IAW CRJ 900 AMM 56-12-01-000/400-801-PSA. REQUIRES CURE TIME, OPS CHECK AND LEAK CHECK. PERFORMED OPS TEST OF WINDOW TEMPERATURE CONTROLLER IAW CRJ 900 AMM 30-41-06-710-801.OPS CHECK GOOD. PERFORMED LEAK CHECK OF L/H WINDOW IAW CRJ 900 AMM 56-12-01-400-801-A01-PSA. LEAK CHECK GOOD.