Came out today for a leaking issue on a Lennox furnace model #G50UH-60D-135-03, serial #5802E38041. Upon arrival the homeowner stated that the drain line was leaking. Upon inspection I tested the drain line with several bottles of water to see if the system was clogged or leaking. The system was leaking at the 90° elbow. I cut out the elbow and installed a new one the caused the drain line to move 2 inches to the left. Once the pvc glue was dry I tested the drain line with several bottles of water. In my professional opinion I believe that the drain line froze from the cold weather over the weekend and this caused the pvc elbow to crack. The system is operating properly at this time.