The writing on this site is general information about air conditioning and heating systems in San Diego County homes, shared to help homeowners understand their equipment and their options. It is not a diagnosis of your system. Homes and equipment vary, even on the same street and in the same band of the county, and the cause of a symptom in one house can be a different cause in the next. Price ranges are typical planning ranges for budgeting, not quotes; your price is confirmed by the contractor before work begins. Any guidance here about shutting down a system, checking a thermostat, or inspecting a unit is offered for situations a homeowner can safely look at; anything involving refrigerant, gas lines, or opened electrical panels belongs to a professional visit. Nothing on this site creates a warranty, a service agreement, or a contractor-client relationship.