Upon arrival, I conducted a thorough inspection of the furnace system. The initial assessment revealed that the furnace was not operating at optimal efficiency. I identified a clog in the drain line as the primary issue. Using specialized tools, I carefully removed the accumulated debris and gunk from the drain. To ensure the clog would not recur, I flushed the drain with a mixture of warm water and vinegar. This solution effectively cleared the blockage and restored proper drainage. The furnace is now running smoothly, and I verified its performance to ensure it meets the required standards.