Today (12/3/25) the heat exchanger was replaced and the blower wheel was removed and cleaned. The belt tension on the new belt was rechecked. After the replacement work the left 2 burners would not light. The burners were removed and their fuel rails were cleaned. The rooftop unit returned to proper heating after all of today’s work was completed. The estimate is below for reference. Thank you, Jon and Diego ————————————————- Quote to replace the failed heat exchanger in the Lennox package unit serial 5613E10390. Price includes the factory parts and labor. The existing heat exchanger has rust holes in the top tubes under the blower that were found during the recent blower assembly removal for cleaning. This unit has the heating mode disabled for safety until repairs can be made. Photos attached of the holes and the flue outlet that is sooted up from the breached exchanger.