John Deere CAB171 – CAB: Heating, Ventilating, and Air Warning

This fault code is logged by the Cab Control Unit (CAB) when the voltage signal from the cab's inlet air temperature sensor is outside of its normal operating range. The sensor provides feedback to the CLIMATRAK automatic temperature control system, and a faulty sensor or circuit will lead to improper operation of the heating and air conditioning system.

• 9470 STS
• 9570 STS
• 9670 STS
• 9770 STS
• 9870 STS
• 6020-6420S Series

1. 1

   Check the sensor's wiring harness for any visible damage, such as chafing, corrosion on the connectors, or rodent damage

2. 2

   Use the machine's diagnostic display to determine if the code is active or stored (a stored code may indicate an intermittent issue)

3. 3

   Inspect the cab air filters (both fresh air and recirculation) and clean or replace them if they are clogged

4. 4

   Ensure the condenser and evaporator cores are clean and free of debris

5. 5

   Check all HVAC-related fuses to ensure they are intact

6. 6

   Using a multimeter, check for an open circuit or a short to ground in the sensor's wiring

7. 7

   Verify that the sensor is receiving the correct reference voltage from the CAB controller

1. 1

   Prepare machine for service

   Park the machine on a level surface, turn off the engine, and engage the parking brake. Allow the engine and coolant to cool down before starting work.

2. 2

   Access the sensor

   Remove access panels around the cab's HVAC unit. For STS combines, access the area behind the training seat. On some tractors, this may involve removing side panels or covers near the A/C compressor.

3. 3

   Disconnect and remove old sensor

   Carefully release the locking tab and disconnect the electrical connector from the sensor. Unscrew the old sensor from its port. Be prepared for a small amount of coolant to leak if the sensor is located in a coolant line.

4. 4

   Install the new sensor

   Ensure the new sensor has a new O-ring or appropriate sealant if required. Thread the new sensor into the port by hand to avoid cross-threading, then tighten to the manufacturer's specified torque.

5. 5

   Reassemble and test

   Reconnect the electrical connector securely. Reinstall any panels or covers that were removed. Start the machine, clear the fault codes from the diagnostic display, and operate the HVAC system to verify it is functioning correctly.