Error Code F5 in Air Conditioners: Diagnosis and Solutions

The F5 error code in air conditioning systems is generally linked to the temperature sensor, specifically the one located on the thin or discharge pipe of the compressor. However, the meaning of this code may vary depending on the brand of the equipment. Below are the possible causes and steps to resolve this issue.

Brands Associated with the F5 Code

The F5 code may appear on equipment from various brands, including:

• Toshiba
• Electrolux
• Gree
• Trane

For Sharp, the F5 code refers to the temperature sensor that monitors the temperature of the conditioned space. On the other hand, for manufacturers such as Bosh, York, or Carrier (when the code appears on the outdoor unit), the F5 code is linked to a malfunction in the outdoor unit fan. For certain Midea models, it may indicate issues with the condenser fan or the temperature sensor.

Diagnosing the Temperature Sensor

If the F5 code is related to the temperature sensor, follow these steps to diagnose and resolve the issue:

1. Turn off and clean the unit
   • Disconnect the unit from the power supply and wait a few minutes before reconnecting it.
   • Clean the air filters and heat exchangers of the indoor and outdoor units if possible.
2. Visual inspection of the sensor
   • Check the position and cleanliness of the sensor.
   • Inspect the sensor’s cables and connections for damage or loose contacts.
3. Testing the sensor
   • Disconnect the sensor from the system.
   • Set a multimeter to the kilo-ohm scale (usually 20 kilo-ohms) and measure the resistance at the sensor’s terminals.
   • The measured value should be neither zero nor infinite; otherwise, the sensor is faulty.
   • Heat the tip of the sensor with your hand while measuring; the value in kilo-ohms should decrease.
4. Verification with a value table
   • If you have access to the equipment’s catalog and a resistance-temperature table, compare the measured value with the expected value for the current temperature.
5. Replacing the sensor
   • If necessary, replace the sensor with an identical model that has the same value table to ensure proper functionality.
6. Measuring the sensor’s power supply
   • If the sensor appears to be in good condition, verify whether the electronic module is supplying the correct power.
   • Connect the sensor, turn on the unit, and use the multimeter in DC voltage mode to measure if the voltage is close to 2.5 V.

Diagnosing the Outdoor Unit Fan

If the F5 code indicates an issue with the outdoor unit fan (as with Bosh, York, or Carrier), follow these steps:

1. Check for cleanliness
   • Ensure that the air filters and heat exchangers are clean.
2. Manually check the fan blades
   • With the unit turned off, try to rotate the fan blades manually to rule out bearing issues.
3. Inspect electrical connections
   • Check the fan’s electrical connections for loose contacts or damaged cables.
4. Test electrical capacitors
   • If the fan uses electrical capacitors, measure their capacitance with a multimeter and compare it to the value specified on the capacitor. Ensure the capacitor is discharged before performing the measurement.