Upon inspection, it was determined that the heat exchanger in the furnace needed replacement, as it was under warranty. I proceeded to replace the heat exchanger and the main limit. The furnace was disassembled carefully to access the components, and the old heat exchanger was removed. The new heat exchanger was installed, followed by the main limit. After reassembling the furnace, I tested the heating system to ensure it was functioning correctly. The heating system is now operational, and payment was collected upon completion of the work.