At 18:50 Monday evening, Engine and Squad 33 (with 12) assisted Company 31 with a reported "explosion in the backyard" followed by a report of an air conditioner on fire. E33 laid out from the closest hydrant and stretch one line. Truck 31 was investigating at the time, finding an outdoor condensing unit which had been on fire. Crews checked for any extension into the duplex residence. Units cleared within the hour. While this incident was happening, Traffic 33 was already committed on traffic control at Silver Spring Rd and Carlisle Pike due to icy conditions. These were the 8th and 9th calls for the day.