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Zachary GarciaSep 8, 2025
Why is my HTP MODCON1000 showing a 'FAN SPEED ERROR F13 PUMP ON'?
- MMary GarciaSep 8, 2025
If your HTP Boiler displays a 'FAN SPEED ERROR F13 PUMP ON' error, it means the fan isn't running at the commanded speed. Troubleshoot as follows: 1. Check the combustion air fan wiring. 2. Measure the DC voltage from the red fan wire to ground while connected to the fan. It should be between 24 to 40 volts. If it's lower than 24 volts, check for excessive external loads connected to the boiler sensor terminals.









