Controller displays Er2 and solar heating is disabled.

Safety: Turn off power before working on roof sensors. Use proper fall protection when accessing the roof.

• Check controller end: Verify the roof sensor wires are secure at the controller terminals.
• Inspect roof run: Follow the cable up to the Fafco solar array. Look for brittle insulation, breaks, or pulled connections at the sensor.
• Test sensor resistance: Disconnect at the controller and measure resistance. An open reading indicates a failed sensor.
• Replace sensor: Mount a new Fafco roof sensor in the same location, protected from direct metal contact, and secure the cable to prevent movement.