What was found
FLT 1263, BOS-AUS, DIVERTED TO IAD, COCKPIT AIR TO COLD CABIN AIR TOO HOT AND UNBEARABLE. FOUND CONDITIONED AIR SUPPLY DUCT TO FORWARD CABIN DISCONNECTED AT H DUCT. RE-SECURED SAME IAW AMM 21-20-03-400. PERFORMED PAX CABIN TEMP CONTROL TEST IAW AMM 21-62-00-710. OPS CHECK OK. PERFORMED COCKPIT TEMP CONTROL TEST IAW AMM 21-61-00-710. OPS CHECK OK.