F4 code displayed; one or more jet pumps will not start or shut off unexpectedly.

Safety: Turn off power at the breaker before touching the pump or wiring.

• Check for mechanical blockage: With power OFF, access the pump and try to rotate the motor shaft (at the rear fan or shaft end) by hand. It should turn freely. If it is locked, the pump is seized and must be replaced.
• Inspect pump unions: Ensure there is no leak dripping onto the pump motor, which can cause overheating and overload trips.
• Reset thermal overload: Allow the pump to cool for 30–60 minutes with power off. Some motors have a manual reset button on the motor housing; press if present.
• Check wiring and connectors: Inspect the pump cable from the motor to the Hanscraft control pack for damage, burn marks, or loose plugs. Reseat the connector firmly.

If the pump still trips F4 immediately when activated, the motor windings or control board relay may be damaged. Replacement of the jet pump or control board is typically required.