Air conditioners almost always fail on the hottest day of the year — because that's when they work hardest. A spring tune-up is the cheapest insurance against that.
A proper tune-up restores efficiency (a dirty coil or low charge can quietly raise your bill 20%+), catches worn capacitors and contactors before they strand you, and extends the life of the system. For most Bay Area homes, one visit a year in spring is all it takes to sail through summer.
