HVAC in Michigan is a long heating season first, and a humid summer second. Boilers still heat a lot of older houses. Furnaces and heat pumps carry others. A cottage may sit cold for months and then be asked to catch up in a weekend. If the house is cold right now, say so before you describe the equipment. If it is merely weak, say whether every room fails or only the one over the garage.
Lake wind and a badly sealed attic make a furnace look failed when the heat is leaving through the lid of the house. Filters, a collapsed return, and a closed register in a back room do the same trick to cooling in July. Ask what got ruled out before a major part is condemned. Combustion equipment needs a clear flue and enough air. A rusty boiler short-cycling in January is not a filter story, and it should not wait.
Replacement follows the house, not the sticker on the old box. Windows, attic, and ducts change the load. Copying the old size because it fit the closet is how rooms stay wrong. Ducts in a cold crawl or a hot attic need a look before they are reused as they are. A new outdoor unit on an old coil is not the same job as a matched pair. Say if there is no heat tonight.
Southern humidity still spoils comfort in summer even when the day is only warm. Heavy air with a cold supply can mean weak airflow or a coil issue, and the fix starts with a diagnosis. Condensate lines clog. Coils ice when filters are choked. In the snow belt the outdoor unit sits in drifts, so intake and discharge have to stay clear.
Say heat or cooling, year-round house or seasonal cottage, and the town. Have the model plate only if it is easy to read. Do not delay a no-heat call for a hunt through the basement. Call the number on this page.