A house that will not cool in July or heat in January gets uncomfortable fast, and many heating and cooling problems start small. Browse guides on air conditioning and cooling problems, furnaces, heat pumps and heating, and filters and system maintenance that keeps equipment running well. There is also coverage of dehumidifiers and air treatment for sticky, stale indoor air. Start with the symptom you hear, feel, or smell, then work toward the repair or service call it points to.