F1
Honeywell
Indoor Ambient Temperature Sensor Error (Alternate Code)
Honeywell AC displays F1 and does not respond correctly to temperature settings.
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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
Open or shorted indoor thermistor, Loose sensor connector, Damaged sensor harness, Faulty main PCB sensor circuit
How to Fix / Troubleshooting
Safety: Unplug the unit before removing covers.
Steps:
- Reset: Unplug for 5–10 minutes and test again. If F1 returns, continue.
- Locate indoor sensor: Remove the front grille and filter. The indoor sensor is usually near the air intake or attached to the evaporator coil.
- Inspect and reseat: Check the sensor wiring for damage and ensure the connector is firmly seated on the control board.
- Test sensor: Use a multimeter to measure resistance. Replace the sensor if it reads open, shorted, or does not change with temperature.
- Replace PCB if needed: If a new sensor does not clear F1, the main control board may be defective and should be replaced.
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Repair Difficulty
Medium
3/5
Required Part
Indoor Temperature Sensor (NTC Thermistor)
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