John Deere 923.03 – ATC: Circulation Blower Motor Circuit Voltage High

The ClimaTrak™ controller registers an excessively high voltage at line 956, which leads to the fan motor driver unit (A59). This indicates that the circuit voltage between the Circulation Blower Motor and the Blower Motor Driver is too high, typically caused by a short to a supply lead somewhere in the circuit.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6020-6920 series
• 7715
• 7815
• 7720
• 7820
• 7920
• 8130
• 8230
• 8330
• 8430
• 8530
• 8230T
• 8330T
• 8430T
• 9230
• 9330
• 9430
• 9530
• 9630
• 8RT series
• CH570
• CH670

1. 1

   Restart the engine to verify if the active Service Code reappears, as a system reset may clear communication message errors.

2. 2

   Acknowledge the code by pressing the select switch on the CommandCenter to clear the display.

3. 3

   Inspect the wiring harness specifically at line 956, which connects the ClimaTrak controller to the fan motor driver unit (A59).

4. 4

   Test the circuit voltage between the Circulation Blower Motor and the Blower Motor Driver to check for a short to a power/supply lead.

1. 1

   Power Down

   Turn off the engine and disconnect the battery ground to ensure safety while working on the electrical system.

2. 2

   Access the Blower Motor Driver

   Locate the blower motor driver unit (A59) and the circulation blower motor, typically found within the cab roof or HVAC housing depending on the specific machine model.

3. 3

   Inspect Wiring

   Visually inspect line 956 and the surrounding wiring harness for chafing, melted insulation, or pinched wires that could cause a short to voltage.

4. 4

   Repair Wiring

   If a short is found in the harness, repair the damaged wire(s) using OEM-approved splicing methods and heat shrink, or replace the affected harness section.

5. 5

   Test/Replace Driver

   If the wiring is intact, the blower motor driver (resistor/controller) has likely failed internally, causing it to pass excessive voltage. Replace the blower motor driver.

6. 6

   Test/Replace Motor

   Check the blower motor itself for internal shorts. If the motor is drawing incorrect voltage or has burnt out due to the driver failure, replace the blower motor.

7. 7

   Reassemble and Clear Codes

   Reconnect the battery, start the machine, and operate the ClimaTrak system to ensure the code does not return and full temperature control is restored.