Fendt 10.1.35 – Central Electrical System ECU (A038 / A111) or Air Conditioning Control ECU (A053 / A112): Output temperature sensor 2

The sensor responsible for measuring the temperature of the air blowing out of the HVAC system is registering as 'Function non-operable', causing the air conditioning system to default to running in emergency mode.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• Fendt 300 Vario (COM III)
• Fendt 400 Vario (COM III)
• Fendt 700 Vario (COM III / S4)
• Fendt 800 Vario (COM III / S4)
• Fendt 900 Vario (COM III / S4)

1. 1

   Access the HVAC unit and visually inspect Output Temperature Sensor 2, its wiring harness, and connector for corrosion, moisture, or chafed wires.

2. 2

   Disconnect the sensor and measure its resistance across the pins with a multimeter (resistance should change smoothly with ambient temperature; infinite or zero resistance indicates failure).

3. 3

   Turn the ignition ON and measure the connector on the harness side to ensure the ECU is sending the proper 5V reference voltage to the sensor.

4. 4

   Test the signal and ground wires for continuity from the sensor connector back to the Central Electrical / HVAC ECU to rule out a broken wire in the cab harness.

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the battery ground if working near the central electrical board.

2. 2

   Access the HVAC Unit

   Unscrew and remove the cab roof maintenance cover to access the HVAC evaporator and blower assembly.

3. 3

   Locate the Sensor

   Find Output Temperature Sensor 2, which is inserted into the air distribution ducting or directly downstream of the evaporator core.

4. 4

   Remove the Sensor

   Disconnect the electrical plug and carefully pull the faulty sensor out of the duct (usually held by a twist-lock mechanism or a small retaining screw).

5. 5

   Install the New Sensor

   Insert the replacement OEM sensor into the duct and secure it. Reconnect the electrical plug, ensuring it clicks into place.

6. 6

   Reassembly

   Reinstall the cab roof maintenance cover.

7. 7

   Clear Codes

   Turn the ignition on and use the tractor's terminal or the FENDIAS diagnostic software to clear fault code 10.1.35.

8. 8

   Test Operation

   Start the tractor and turn on the air conditioning. Verify that the system exits emergency mode and that the cab temperature regulates correctly.