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carlcolemanAug 7, 2025
Why is my A.O. Smith AWH-35 Water Heater heat pump not running - high pressure fault?
- CCandace SalinasAug 7, 2025
If your A.O. Smith Water Heater's heat pump isn't running due to a high pressure fault, first ensure the thermostat setting does not exceed 140°F. If the room temperature is over 95°F, keep the heat pump off until the temperature is within the operating range. Also, check for low water flow; this could be due to the unit pump not operating, excessive piping length between the heat pump and storage tank, scale buildup in the heat exchanger, or partially closed shut-off valves. Possible solutions include replacing the unit pump, reducing piping length or adding a booster pump, cleaning the heat exchanger with a mild acid wash, or fully opening all shut-off valves.