Jacuzzi pool heater display shows F7; heater will not respond to thermostat commands.

Safety first: Turn off power before accessing the control compartment.

Steps to address F7:

• Power cycle the heater: Turn off the breaker for 2–3 minutes, then restore power. Sometimes transient faults clear; if F7 returns, continue troubleshooting.
• Inspect water temperature sensor: Locate the thermistor on the water manifold. Check that it is fully inserted and secured. Inspect the harness for damage or corrosion at the connector.
• Test sensor resistance: With power off, disconnect the sensor and measure resistance with a multimeter. Compare to Jacuzzi’s temperature/resistance chart. A reading far out of range indicates a failed sensor.
• Replace sensor if needed: Install a Jacuzzi-compatible water temperature sensor, ensuring good thermal contact with the manifold.
• Control board check: If a known-good sensor still results in F7, the main control board may have a failed input circuit and require replacement by a professional.