Your HVAC care plan guide 566

A good HVAC system rarely fails all at once. More often, it loses efficiency in small, expensive ways. A filter loads up with dust, a coil gets coated with film, a drain line starts to clog, a thermostat drifts out of calibration, and a safety switch that should have been tested last season never gets touched. The system keeps running, so the problem hides in plain sight until the first hot spell, the first cold snap, or the utility bill arrives with a number that feels out