F1
Comfortmaker Indoor Ambient Sensor Out of Range (High/Low Temperature)

Display shows F1 and unit may run erratically or not at all

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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

Room sensor exposed to direct sunlight or heat source, Sensor not in return air stream, Faulty room thermistor, Indoor PCB misreading sensor

How to Fix / Troubleshooting

Safety: Turn off power to the indoor unit before accessing sensors.

Steps:

  • Check sensor location: Ensure the Comfortmaker room sensor (if remote) is not installed near windows, lamps, or electronics that can cause false readings.
  • Inspect sensor wiring: Look for loose or damaged wires between the sensor and indoor PCB.
  • Test sensor resistance: With power off, disconnect and measure resistance. Compare to the manufacturer's chart. Replace if out of range.
  • Relocate sensor if needed: Move the sensor to a location with representative room air and away from drafts.

Note: If the sensor is integrated into the PCB and F1 persists, the indoor board may need replacement.

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Repair Difficulty

Medium 3/5

Required Part

Indoor Room Temperature Sensor (Thermistor)
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