Jacuzzi pool heater shows FC and will not respond to external controls (automation).

Safety first: Turn off power before working on low-voltage wiring.

Steps to resolve FC:

• Check control mode: On the Jacuzzi heater interface, verify that the control mode (local/remote) is set correctly for your installation. If using automation, it should be in remote mode per the manual.
• Inspect automation wiring: Locate the low-voltage terminals for external control. Confirm that the wires from the pool automation panel are landed on the correct terminals and are firmly tightened.
• Test without automation: Temporarily disconnect the automation wires and set the heater to local control. If FC clears and the heater operates normally, the issue is in the automation system or wiring.
• Check cable integrity: Look for damaged insulation, splices, or corrosion in the communication cable. Replace if suspect.

If FC persists with correct wiring and local control, the external control interface on the Jacuzzi control board may be defective and require replacement.