John Deere 000923.04 – ATC: Circulation Blower Motor Circuit Voltage Low

The Automatic Temperature Control (ATC) system has detected an abnormally low voltage in the electrical circuit connected to the cab's circulation blower fan motor driver unit (A59). This typically indicates an open circuit or a short to ground. When this fault is active, it may affect the operation of the module, leading to improper performance or failure of the component, and the controller will restrict the functionality of the automatic temperature control system.

• 6020 to 6920S Series
• 7630
• 7720
• 7730
• 7820
• 7830
• 7920
• 7930
• 8110
• 8130
• 8210
• 8230
• 8310
• 8330
• 8410
• 8430
• 8530
• 9120
• 9220
• 9230
• 9320
• 9330
• 9420
• 9430
• 9430T
• 9520
• 9530
• 9530T
• 9620
• 9630
• 9630T
• 4730
• 4830
• 4930
• 4940

1. 1

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

2. 2

   Ensure the cab's recirculation air filter is not clogged

3. 3

   Attempt to clear the diagnostic trouble code and perform a functional test to see if it returns

4. 4

   With the ignition on, turn the fan speed control and temperature control to their lowest (off) settings, then check fan controls via diagnostic address ATC005: slowly turn fan speed control through its full range; display should change from '000' to between '038' and '100'. An 'Err' display indicates a circuit or driver unit fault

5. 5

   Visually inspect the fan motor driver unit (A59) and its electrical connectors in the heater/evaporator housing for damage, dirt, corrosion, or bad, loose, widened, or pushed-back pins

6. 6

   Perform a Circuit/Harness Test for Fan Motor Driver Unit (A59) per section 245-ATC of the technical manual to check for continuity and shorts to ground or power

1. 1

   Ensure safety

   Lower all equipment, stop the engine, remove the key, and disconnect the battery ground strap to prevent electrical shorts.

2. 2

   Access blower motor assembly

   Remove the cab roof panels and covers to access the roof-mounted HVAC unit where the cab fan roof module is located.

3. 3

   Address wiring issues

   If the circuit/harness test revealed a problem, repair broken wires, clean corroded terminals, or replace damaged connectors. Perform an operational check after repairs.

4. 4

   Replace blower motor assembly

   If wiring is intact and the fault lies within the fan motor or driver unit, replace the entire ATC fan/motor assembly. The Fan Motor Driver Unit (A59) is integrated and not sold separately.

5. 5

   Install and reassemble

   Install the new blower motor assembly, ensuring all electrical connections are secure. Reassemble the roof panels and any other removed components.

6. 6

   Test system

   Reconnect the battery, start the tractor, and test the ClimaTrak system to ensure it functions correctly and the fault code does not reappear.