Solar system runs at night, cooling the pool instead of heating it.

Safety: Turn off power before changing sensor wiring.

• Check mode: Ensure the controller is set to HEAT mode, not COOL or special modes that might run at night.
• Compare readings: At night, the roof should be cooler than the pool. If the controller shows the opposite, the sensors may be swapped.
• Swap sensor leads: At the controller, swap the pool and roof sensor wires to their correct terminals and secure them.
• Relocate roof sensor: If the roof sensor is near a warm vent or light source, move it to a representative spot on the Fafco panels.