John Deere 923.04 – ATC (Automatic Temperature Control / ClimaTrak) / ETC (Environmental Temperature Control): Circulation Blower Motor Circuit Voltage Low / Fan Motor Driver Unit, Grounded or Open Circuit

Triggered when the climate controller registers an excessively low voltage on the line (e.g., line 956) leading to the Fan Motor Driver Unit (A59), or when the Power Module (HF) PC6 measures a current exceeding 30 amps at one or both fan motor outputs (leads 2043 and/or 2047) while the fan motors (M07 and M10) are switched on. This condition indicates a short to ground or an open circuit in the blower motor circuit.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6020 to 6920S
• 6120 to 6420
• 6120L to 6520L
• 6230
• 6330
• 6430
• 7715
• 7815
• 7720
• 7820
• 7920
• 8230T
• 8330T
• 8430T
• 8R/8RT/8RX Series
• 9430
• 9530
• 9630
• 9R/9RT/9RX Series
• 8000 series harvesters
• 9000 series harvesters

1. 1

   Check the power supply to the Fan Motor Driver Unit (A59) / Power Module (HF) PC6

2. 2

   Visually inspect the wiring harness and connectors for the fan motor outputs (leads 2043, 2047, or 956) for signs of shorts to ground, damaged insulation, exposed wires, or pinched cables

3. 3

   Use a multimeter to measure the current draw of the cab fan motors (M07 and M10) to ensure they operate under 30 amps

4. 4

   Perform a continuity test between the ATC controller and the fan motor driver unit to rule out an open circuit in the harness

1. 1

   Access the Blower Assembly

   Gain access to the cab roof or HVAC blower housing (location varies by tractor model).

2. 2

   Test and Replace Fan Motors

   If the multimeter test shows the M07 or M10 fan motors are drawing excessive current (shorted internally), remove and replace the defective blower motor(s).

3. 3

   Inspect/Replace the Power Module

   If the motors test fine but the voltage drop remains, the Fan Motor Driver Unit (A59) / Power Module (HF) PC6 has likely failed internally due to the short. Replace the driver unit.

4. 4

   Repair Wiring

   Fix or splice any damaged, pinched, or shorted wiring in the fan motor circuits. Ensure all connections are secure and properly insulated.

5. 5

   Reassemble and Clear Codes

   Reassemble the HVAC housing, turn the tractor on, and clear the ATC 000923.04 code via the CommandCenter display. Run the ClimaTrak system to verify the blower operates at all speeds without triggering the code.