Fafco Control Enable / Interlock Issue

Solar system never turns on, even when pool is cold and sunny conditions exist.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

External heater interlock open, Fireman switch loop not closed, Automation system not granting solar enable, Fafco controller in OFF mode

How to Fix / Troubleshooting

Safety: De-energize circuits before working on interlock wiring.

  • Verify controller mode: Confirm the Fafco controller is set to AUTO or HEAT and not OFF.
  • Check interlock terminals: If wired to a gas heater or automation, ensure the fireman switch or enable loop is closed when solar should run.
  • Bypass for test: Temporarily jumper the enable terminals (per manual) to see if the solar system activates. Remove jumper after testing.
  • Coordinate with automation: If integrated with a pool automation system, verify that solar is enabled in the automation programming and that there are no conflicting schedules.
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Repair Difficulty

Medium 3/5

Required Part

Fafco Controller Board
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