While returning from a response, the 2001 Pierce HP75 Ladder Truck that a Braden River, FL Fire Lieutenant and his driver were riding in experienced an explosion in the high pressure line of the vehicle’s air conditioning system. The resulting pressure immediately bore a hole through the engine cover and vented freon into the officers area of the cab where our Fire Lieutenant was seated. The hole that resulted was just inches from the Lieutenant who was shaken up by the incident. The situation is being investigated by the safety and maintenance committees.