Question on Tune Up Timing

https://johnnyvlrd276.valiantfield.com/posts/attic-heat-and-ductwork-problems-behind-ac-repair-in-north-fort-worth-explained-by-comfort-experts-3

Question on Tune Up Timing Does anyone know if spring or fall is better for a tune-up? Not sure when it makes the most sense for an older system in Summerfields, since the AC works hardest in summer but the furnace matters in winter