Here's the harsh truth: nearly all HVAC failures happen because someone missed a step. Did not calculate the load correctly. Used undersized equipment. Misjudged the insulation needs. We've personally fixed dozens of these failures. And every time, we file away another learning. Like in 2017, when we decided on adding WiFi controls to every system. Why? Because Sarah, our senior tech, got frustrated of watching homeowners burn money on poor temperature settings. Now clients save 20-30% yearly.