“It’s on and it’s blowing, but it’s not cold.” That sentence is most of our summer phone calls. A lot of those visits end at a thermostat, a filter, or an outdoor unit that never started.
Do these in order
- Mode and setpoint. Cool, not Off. Setpoint about 3° below the room. Fan Auto, not On — On will blow room air and fool you.
- Filter. Light test. A packed filter ices the indoor coil. Ice makes warm air. Replace the filter, thaw (Cool Off, fan On), then try again. If it ices the same day, stop.
- Outdoor unit. Is the fan spinning while the thermostat is calling? Silent and still is usually power, a capacitor, or a contactor — not a hose-and-hope.
- Split. After ten minutes, the vent should feel clearly colder than the hallway. If you have a kitchen thermometer, supply vs return is the adult version. Under about 8° of difference while running is a fault.
The Toolbox is those gates with Skip if you do not want to crawl around. It is not a diagnosis. It is so we are not starting from zero.
Stop and call
Burning smell, gas smell, smoke. A breaker that trips again after one reset. Standing water at the air handler. Those are not filter day.
Book a visit. Bring what you already saw.