Fendt 10.1.3A – A053 Air Conditioning Control Unit (HVAC ECU) / A038 or A111 Central Electrical System ECU: Checksum error, air conditioning (Adr 1000d- 1125)

The system cannot read the saved configuration properly. As a result, default parameters are read from the flash memory. The air conditioning system will typically run in an emergency/default mode, and you may lose fine climate control functions.

• 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 & SCR Tier 3b)
• Fendt 800 Vario (COM III)
• Fendt 900 Vario (COM III & SCR)

1. 1

   Check for accompanying HVAC codes on the terminal (e.g., 10.1.3B for overheating protection or 10.1.3C for solar sensor failure)

2. 2

   Verify the tractor's system voltage and check the fuses supplying the central electrical system (A038/A111), as severe voltage drops or battery disconnects can trigger checksum errors

3. 3

   Test HVAC operation to confirm if the air conditioning is running in emergency mode (e.g., fans running at a fixed speed, inability to adjust temperature setpoints)

1. 1

   Connect diagnostic tool

   Connect the FENDIAS diagnostic laptop to the tractor's diagnostic port.

2. 2

   Perform EOL programming

   Access the A053 (or A038/A111) module and perform the EOL programming procedure to re-flash the correct parameters to the ECU.

3. 3

   Clear fault memory

   Clear the fault memory and cycle the tractor's key to verify the code does not return.

4. 4

   Replace control unit

   If the EOL programming fails to write to the flash memory, or if the code immediately returns, replace the A053 Air Conditioning Control Unit (or the Central Electrical System ECU, depending on the model's specific wiring) and subsequently program it.