Question on Tune Up Timing

https://telegra.ph/Comfort-Experts-AC-Repair-North-Fort-Worth-Family-Owned-Since-1962-11-14

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