How long does an average A/C system last before I should consider replacement? Chris in Prescott Valley

Chris, this can vary depending on the manufacturer, maintenance schedule and the use of your equipment.  In an idea situation, meaning that you have properly maintained the system, that it was adequately sized for your home, you should expect the unit to last 10-20 years.  Regular maintenance can extend the life of a system by as much as 5-10 years.