Solar system runs at night or on cloudy days, cooling the pool instead of heating it.

Safety first: Turn off power to the controller before changing wiring.

• Verify sensor wiring: Confirm that the pool sensor is connected to the pool terminals and the roof sensor to the solar terminals on the controller.
• Check sensor locations: Ensure the solar sensor is on the roof near the Heliocol panels and the pool sensor is in the pool plumbing, not reversed.
• Review controller settings: In the setup menu, verify that the controller is using the correct sensor inputs for solar control logic.
• Test sensor readings: Compare displayed pool and solar temperatures to actual conditions. Replace any sensor with obviously incorrect readings.