Controller displays FLO or FLOW and solar heating will not start even when the pump is running.

Safety first: Turn off the pool pump and any automation power before working on plumbing or wiring. Depressurize the system by opening the filter air relief.

• Check filter pressure and cleanliness: Verify the pool filter pressure is within normal range. If pressure is high, backwash or clean the filter to restore flow.
• Verify solar isolation valves: Ensure the solar supply and return valves to the Heliocol array are fully open. Manually move valve handles to the open position and confirm actuator cams are not limiting travel.
• Inspect Heliocol panel headers: Look for crushed, kinked, or obstructed PVC lines feeding the Heliocol manifolds. Remove any visible debris from header unions and flush lines if necessary.
• Check the flow switch: Locate the flow switch installed in the solar feed line. Confirm the arrow on the body points in the direction of flow. Inspect wiring connections at the controller and tighten any loose terminals. If the paddle is broken or stuck, replace the flow switch.
• Test operation: Restore power, start the pump, and enable solar mode. Confirm the FLO code clears and the solar valve opens.