Arrived on site to perform Fau maintenance on 15 year old trane system. Cycled system for heating. Verified proper heating sequence of operations. Temperature rise across heat exchanger is within allowed range for unit. Indoor blower wheel is slightly dirty. Indoor blower motor amp draws are within range and secondary motor control is within range. Tested and verified heating safeties and components, all check good. Pulled blower motor to inspect heat exchanger. Replaced both 1 inch filters. Gas line does not have a sediment trap before it goes into the valve. Also noticed that condensation lines do not have any condensation safety switches on either primary or secondary line. Furnace is sitting on wooden 2x4 stands instead of metal stands. Went over all findings and recommendations with homeowner. Cycled system, system is fully operational upon departure.