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Why is my AC running but not cooling?

Short answer

Common causes are a dirty filter, a frozen coil, a dirty outdoor unit, or low refrigerant. Check the filter and thermostat; the rest needs a tech.

Rules differ by state. This is general information, not legal or professional advice.

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Official sources

Energy Saver (U.S. Dept. of Energy)energy.gov
CDC: carbon monoxide safetycdc.gov
Ready.gov: extreme heat and winter weatherready.gov