Display shows LO or LOW TEMP and unit will not start or cycles off quickly.

Safety first: Disconnect power before accessing sensors or control board.

• Check outdoor temperature: Verify the actual air temperature with a thermometer. If it is below the unit's specified minimum, the LO indication is normal and the heater must wait for warmer conditions.
• Inspect ambient air sensor: Locate the air sensor near the evaporator coil or control compartment. Ensure it is not touching hot components or exposed to direct sunlight, which can skew readings.
• Check sensor wiring: Look for damaged insulation or loose connectors at the control board. Reseat the connector.
• Compare readings: If the display shows a very different air temperature than actual, the sensor may be faulty. Replace with an AquaCal‑compatible ambient air sensor.
• Control board check: If a new sensor does not correct the reading, the control board may be defective and should be evaluated by an AquaCal technician.