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The compressor in a central AC system works hardest at the moment it starts, and a compressor that starts and stops repeatedly across a full cooling season puts real stress on the contactor and the motor windings. Homes in Boone County, MO run cooling about four months a year, from June through September. A contractor diagnosing a failed or struggling unit here checks those cycling components first: the contactor for pitting, the capacitor for signs it has been carrying a weakened start, the condenser fan motor for bearing wear. A short-season system might hide the same faults for another year. Here, the accumulated starts catch up with marginal parts before a homeowner notices anything is wrong.
Ductwork in a house this old tends to get overlooked when a system acts up, because the complaint comes from the equipment and that is where attention goes first. Half the homes in Boone County, Missouri were built in 1991 or earlier (2020-2024 ACS 5-year). A contractor opening a failed unit in stock like this finds the compressor and the coil, but the duct runs behind the walls are the same ones that were there long before that unit was installed. If a part has gone out of production, a good contractor says so before the repair starts and prices accordingly. If the ducts are leaking, a refrigerant recharge will not fix the comfort problem.
The Parts of a Central AC a Contractor Checks First
The outdoor condenser unit sits outside the house, usually on a concrete pad against an exterior wall, and it carries the compressor and condenser coil. Both are common repair targets. The compressor is what drives the whole system, and the condenser coil sheds heat to the outside air, so when either one fails, the system stops doing its job entirely.
Inside the house, the air handler holds the evaporator coil and the blower fan. The evaporator coil pulls heat out of your indoor air, and the blower pushes that air through the ducts. The refrigerant line set runs between the two units, and the thermostat on a wall in the living space tells the system when to run. Any of these can be the source of a problem.
The drawing shows a typical central AC layout, and a licensed contractor determines which components apply and what work is needed in your specific home.
Get matched in Boone CountyBoone County by the numbers
84 severe weather events were recorded in Boone County, Missouri 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 Boone County, Missouri were built in 1991 or earlier (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesBoone County, Missouri holds 81,675 housing units (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesOwners occupy 57.7% of the occupied homes in Boone County, Missouri (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesCodes & Standards Behind AC Repair in Boone County, Missouri8 sourced rules and standards
What HVAC Repair Looks Like in Boone County
Split-system central air conditioners rated below 45,000 Btu/h manufactured on or after January 1, 2023 must meet a federal minimum of 13.4 SEER2.
Split-system central air conditioners rated at or above 45,000 Btu/h manufactured on or after January 1, 2023 must meet a federal minimum of 13.4 SEER2.
Split-system central air conditioners manufactured between January 1, 2015 and December 31, 2022 had to meet 13 SEER, the metric that preceded SEER2.
Single-package central air conditioners manufactured on or after January 1, 2023 must meet a federal minimum of 13.4 SEER2.
Space-constrained central air conditioners manufactured on or after January 1, 2023 must meet a federal minimum of 11.7 SEER2.
Federal efficiency standards for split-system central air conditioners and heat pumps are set on each certified combination of outdoor unit and indoor coil rather than on the outdoor unit alone.
Residential and light commercial air conditioning and heat pump systems assembled in the field, including mini-splits and unitary systems, may not be installed on or after January 1, 2025 using a refrigerant with a global warming potential above 700.
A field-assembled system whose specified components were all manufactured or imported before January 1, 2025 carries no installation compliance date under the refrigerant restrictions and may still be installed.
Severe Weather Events in Boone County
Weather puts real hours on cooling equipment. Hard starts, sustained runs, and power fluctuations from storm activity all add wear that shows up as repair calls, and how much of that load a system carries depends on what the local climate delivers.
84 severe weather events, 2015–2024. Source: NOAA National Centers for Environmental Information, Storm Events Database.