You should inspect and clean out the drain lines on your furnace annually. The drain lines can back up and cause the furnace to shut itself down.

If the drain lines on the outside of the furnace clog, it could cause water to back up leaving a big mess on the floor as well as stop the furnace from working.

If any of the drain line hose inside the furnace leak, it can cause rusting since the water within the furnace is acidic. Rust and acid can shorten the life of the furnace considerably.