Question on Tune Up Timing

https://telegra.ph/AC-Repair-in-North-Fort-Worth-and-Plumbing-Help-Under-One-Roof-at-Comfort-Experts-11-10

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