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A heat pump asked to carry a long heating load puts its refrigerant circuit, reversing valve, and defrost board through repeated cycling across cold months. Homes in Union County, SD run heat about eight months a year, from October through May. As outdoor temperatures drop, a heat pump's capacity falls too, which means the system runs longer cycles to hold indoor temperature, pressing the compressor harder than a mild winter would. Contractors diagnosing a repair here check the defrost controls and refrigerant charge before anything else, because those are the components the heating season degrades first.
Ductwork laid in for a furnace and later asked to carry a heat pump runs at pressures and volumes it was not designed for, and the joints and seals that have been holding for decades are often the first thing a contractor finds when refrigerant charge is off or airflow is uneven. Half the homes in Union County, South Dakota were built in 1993 or earlier (2020-2024 ACS 5-year). That means the repair story in a typical Union County house frequently extends past the unit itself. A contractor who opens the heat pump and finds a compressor within spec will keep tracing back through the duct runs, looking for the restriction or the leak that sent the system into a fault state in the first place.
The Parts of a Heat Pump a Contractor Checks First
The outdoor unit sits outside the house and holds the compressor and the condenser coil. The compressor is the part contractors go to early: when a heat pump stops moving heat the way it should, a failed compressor or a refrigerant problem at the coil is often where the fault lives. The air handler sits inside, usually in a utility closet or basement, and its blower and evaporator coil are checked alongside the outdoor unit.
The reversing valve is inside the outdoor unit and is what lets a heat pump heat in winter and cool in summer. A stuck or leaking reversing valve shows up as a system that works in one mode but not the other. The expansion valve and refrigerant lines run between the two units, and a contractor reads their pressures to find leaks or blockages that the components themselves would not reveal.
The drawing shows the general layout of these components, and a licensed contractor determines what applies to your specific house and system.
Find a contractor in Union CountyUnion County by the Numbers
118 severe weather events were recorded in Union County, South Dakota 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 Union County, South Dakota were built in 1993 or earlier (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesUnion County, South Dakota holds 7,588 housing units (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesOwners occupy 73.1% of the occupied homes in Union County, South Dakota (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesSevere Weather Events in Union County by Year
Extreme weather puts heat pumps under stress, and how hard a system works over its life is shaped by what the local climate throws at it. Repair needs in Union County reflect that history, which is why local weather data belongs alongside any honest conversation about heat pump service here.
118 severe weather events, 2015–2024. Source: NOAA National Centers for Environmental Information, Storm Events Database.