Controller repeatedly shows rES or RESET REQUIRED and will not stay in AUTO mode.

Safety: Turn off power at the breaker before removing the controller from the wall or accessing internal components.

• Stable power: Verify the controller is on a dedicated, properly sized circuit. Loose line connections in the service panel or at the controller can cause resets.
• Factory reset: Follow the Fafco manual to perform a factory reset of the controller settings, then re-enter pool setpoints and modes.
• Inspect internal battery: If the controller uses a coin-cell or small backup battery, replace it with the same type and polarity.
• Check for moisture: Look for signs of water intrusion or condensation inside the controller housing. Dry thoroughly and improve weather protection if needed.
• Replace controller if unstable: If rES persists after stable power and reset, the controller board memory is likely failing and should be replaced.