If everything seems to be working but it's not heating or cooling, check the contactor that turns the compressor on at the outdoor unit. Make sure you have power through both legs of the contactor because sometimes they will build up carbon an the contacts and not allow normal electrical flow. If the contactor is pulling in and there is power going through it, you'll need to check the run capacitor and the compressor itself
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If everything seems to be working but it's not heating or cooling, check the contactor that turns the compressor on at the outdoor unit. Make sure you have power through both legs of the contactor because sometimes they will build up carbon an the contacts and not allow normal electrical flow. If the contactor is pulling in and there is power going through it, you'll need to check the run capacitor and the compressor itself