John Deere 871.04 – ATC (Automatic Temperature Control): Refrigerant Pressure Sensor Circuit Voltage Low

The Automatic Temperature Control (ATC) unit has detected an abnormally low voltage signal (0 volts) from the air conditioning refrigerant pressure sensor. This indicates a potential open circuit or a short to ground in the sensor's electrical circuit, which disrupts the HVAC system's ability to monitor and control refrigerant pressure and often leads to a loss of cooling.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6020 series
• 6030 series
• 7020 series
• 8030 series
• 9030 series
• 6120-6420
• 7720
• 7820
• 7920
• 8230T
• 8430
• 9430
• 9530
• 9630
• 6M series
• 6R series
• 7R series
• 8R series
• 9R series
• S550
• S650
• S660
• S670
• S680
• S690
• S760
• S770
• S780
• S790
• T-Series
• 444 Loader
• 544 Loader
• 644 Loader
• 744 Loader
• 844 Loader
• 700 Dozer
• 750 Dozer
• 850 Dozer
• Harvesters
• Forwarders

1. 1

   Inspect the wiring harness and connectors associated with the B130 refrigerant pressure sensor (specifically lead 2019) for broken wires, loose connections, or corroded terminals.

2. 2

   Test electrical continuity in the sensor circuit using a multimeter to check for an open circuit (no continuity) or a short to ground (low resistance to ground).

3. 3

   Measure the voltage at the sensor input connector with a multimeter to ensure proper supply voltage is reaching the sensor from the ATC module.

4. 4

   Use a diagnostic tool to verify the operation of the B130 sensor itself to confirm if it has failed internally, assuming wiring and supply voltage are intact.

1. 1

   Locate the Sensor

   Locate the B130 refrigerant pressure sensor on the high-side A/C line.

2. 2

   Repair Wiring

   If the diagnostic checks revealed an open circuit or a short to ground in the harness (lead 2019), repair or replace the damaged wiring and ensure all connections are secure and properly insulated.

3. 3

   Replace the Sensor

   If the wiring is good but the sensor is outputting 0 volts, the sensor is defective. Remove the faulty B130 sensor and install the replacement transducer using a new O-ring.

4. 4

   System Reset

   Turn the tractor on and reset the system via the CommandCenter or diagnostic tool to clear the ATC 000871.04 fault code.

5. 5

   Re-evaluation

   Start the engine and test the HVAC system comprehensively to ensure the A/C compressor clutch engages, the system regulates temperature effectively, and the code does not return.