Gree FJ

What does Gree FJ mean?

FJ means the temperature sensor at the air outlet is open- or short-circuited. The unit registers a temperature-sensor fault and displays FJ.

Symptoms

• Display shows FJ
• In cool/fan/dry the indoor fan runs but compressor and outdoor fan stop; in heat all loads stop
• Unit will not maintain temperature
• Code latches at power-up or shortly after

Common causes

• Air-outlet (DAHT) sensor not connected well
• Temperature sensor damaged
• Connection wire short-circuited or broken
• Main board fault

Diagnostic steps

1. 01

   Check the connection

   Verify the terminal between the air-outlet sensor and the control board is not loose or poorly connected and reseat the sensor.

2. 02

   Inspect for shorts

   Look for a short circuit from tripped-over parts on the board and straighten them.

3. 03

   Verify resistance

   Measure the sensor against the manual's resistance table; replace it with the same model if it reads out of range.

4. 04

   Replace the board

   If sensor and wiring are good, replace the controller board with one of the same model.

When to call a professional

FJ follows the same sensor-test procedure as the other F-series codes and needs a meter plus the resistance table. If a quick reseat does not clear it, or the controller board is suspect, have a licensed HVAC technician confirm the sensor and replace parts as needed.