Check the thermostat’s mode and setpoint, and note whether the system starts, moves air, and cools. Avoid opening equipment panels or handling electrical or refrigerant components.
Describe the problem clearly
Is the system off, running without cooling, leaking, or making a new sound? Tell us when it started and whether the problem affects one room or the whole home.
Look only where it is safe to look
If your filter is safely accessible, note its condition and the replacement date. Keep supply and return grilles clear. If you see ice, leaking water, or damaged wiring, stop troubleshooting and contact a professional.
Ask for findings before deciding on work
Request an explanation of the problem, options, and price before authorizing repairs. Equipment inspection is needed to identify a fault. Room air readings do not diagnose refrigerant, electrical, or compressor problems.
WHAT THE EVIDENCE SAYS
Research behind this question.
Your equipment feels the effects, too
Residential heating and cooling equipment · ENERGY STAR guidance checked September 2026
Dirty coils can reduce cooling, increase runtime and energy costs, and shorten equipment life. A blocked condensate drain can cause water damage and affect indoor humidity.
These are equipment conditions that need inspection. A room particle or humidity reading cannot identify a failed component.