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A heat pump running a long heating season puts its compressor, reversing valve, and refrigerant circuit through sustained cycling. Homes in San Mateo County, CA run heat about seven months a year, from November through May. Contractors diagnosing a failing unit here look at the refrigerant side early, because those components absorb the load of every cold morning the system has worked through. The reversing valve in particular takes wear each time the pump shifts between heating and cooling modes, and a county with a heating season this length gives that valve little rest.
Stock this old has been through enough equipment cycles that the ductwork and electrical were sorted out long before the current heat pump arrived. Half the homes in San Mateo County, California were built in 1966 or earlier (2020-2024 ACS 5-year). What a contractor opens today is a system running in a house that has already adapted to it, which means the repair itself is the story. Worn contactors, refrigerant that has migrated, a compressor drawing more current than it should: those are what drive both the diagnosis and the bill, and the house is not where the answer hides.
The Parts of a Heat Pump a Contractor Checks First
The outdoor unit sits on a pad beside the house and holds the compressor and condenser coil. These are the parts a contractor goes to first when a heat pump stops heating or cooling properly. A failed compressor, a refrigerant leak at the coil, or a seized fan motor in that cabinet are common sources of the problem.
Inside the house, the air handler holds the evaporator coil and the blower that moves conditioned air through the home. The refrigerant lines run between the two units, and the reversing valve inside the system controls which direction the cycle runs. A contractor checks the air handler, the coil, and that valve when the outdoor unit checks out clean.
The drawing shows a typical layout, and a licensed contractor determines which parts apply to your specific system and home.
Get matched in San Mateo CountySan Mateo County, by the numbers
282 severe weather events were recorded in San Mateo County, California between 2015 and 2024.
NOAA National Centers for Environmental Information, Storm Events Database, bulk CSV export, events 2015-01-01 through 2024-12-31.Half the homes in San Mateo County, California were built in 1966 or earlier (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesSan Mateo County, California holds 287,184 housing units (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesOwners occupy 58.5% of the occupied homes in San Mateo County, California (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesCodes & Standards Governing Heat Pump Repair in San Mateo County, California1 sourced rules and standards
Contractor Rules in San Mateo County, California
California requires a state contractor license: it is a misdemeanour to engage in the business of, or act in the capacity of, a contractor in California without one, unless the work is exempt.
Weather Events in San Mateo County
Extreme weather puts heat pumps under load at the exact moments they are least able to shed it. San Mateo County's climate shapes how hard local equipment works and how quickly wear accumulates, which is why weather history belongs on a page about repair.
282 severe weather events, 2015–2024. Source: NOAA National Centers for Environmental Information, Storm Events Database.