Performed furnace maintenance on 2 9 year old carrier units. Cycled systems for heat. Verified proper heating sequence of operations. Cleaned furnace, blower assembly and heating compartment. Ran systems through 20 point inspection checklist. Went over all concerns and recommendations with homeowner. Homeowner is fully aware of the condition of his systems. Wants to hold off on any repairs for now. Cycled system, system is operational upon departure.