John Deere 000923.04 – ATC: Cab Fan Motor Low Voltage

The Automatic Temperature Control (ATC) module has detected an abnormally low voltage on the electrical circuit leading to the fan motor driver unit (A59). This condition indicates a potential short to ground or an open circuit in the cab's circulation blower motor circuit. As a result, the controller will restrict temperature control within the cab, affecting the operation of the fan and the overall cooling system.

• 6020 to 6920S Series
• 7715
• 7815
• 7720
• 7820
• 7920
• 8230T
• 8330T
• 8430T
• 9230
• 9330
• 9430
• 9530
• 9630

1. 1

   Check the cleanliness of the condenser at the front of the tractor

2. 2

   Ensure the cab recirculation air filter is not plugged

3. 3

   Check if the diagnostic trouble code is active or if it regenerates after being cleared

4. 4

   Inspect the power supply to the fan motor driver unit, specifically checking fuses F05/13 and F05/1

5. 5

   With the ignition on, turn the fan speed control and temperature control to their lowest and highest settings to check for proper operation

6. 6

   Visually inspect the fan motor driver unit (A59) and its electrical contacts for any signs of damage or dirt

7. 7

   Perform a detailed circuit and harness test for the fan motor driver unit (A59) to identify any shorts or open circuits

1. 1

   Clear active codes

   If the code was stored but is not currently active, clear the code. If the code reappears, further investigation is necessary.

2. 2

   Address power supply issues

   If the power supply check reveals a blown fuse (F05/13 or F05/1), replace it. If the issue persists and the fuse blows again, investigate the cause of the blown fuse, such as a short circuit.

3. 3

   Clean and repair connections

   If the visual inspection reveals corroded or damaged connectors on the fan motor driver unit (A59), clean or repair them as needed.

4. 4

   Test and replace blower motor

   If the wiring and driver unit appear to be in good condition, test the blower motor by applying a direct 12-volt source to its terminals. If the motor does not run, replace it.

5. 5

   Replace fan motor driver unit

   If the diagnostic tests point to a failure in the fan motor driver unit (A59), it will need to be replaced.

6. 6

   Repair wiring harness

   If the circuit/harness test reveals a short or open circuit, the wiring harness must be repaired or replaced.