John Deere 876 – LCU: CLIMATRAK Compressor Driver Circuit Fault

The Left Control Unit (LCU) has detected an abnormal condition in the CLIMATRAK air conditioning compressor driver circuit. This indicates an open circuit, short circuit, over-voltage, or over-temperature condition in the electrical circuit between the control unit and the A/C compressor clutch, or within the control unit's driver itself. The system disables the compressor to prevent damage.

• 7330 Premium
• 6930
• 7430E
• 7530E

1. 1

   Perform a visual inspection of the A/C compressor, clutch, wiring, and connectors for damage, corrosion, or loose connections

2. 2

   Check fuses F05/12 or F07/12 for a potential power supply fault to the compressor clutch

3. 3

   Attempt to manually rotate the compressor clutch hub back and forth to ensure the compressor is not seized

4. 4

   Ensure the radiator and A/C condenser are clean and free of debris, and check cab air filters to rule out over-temperature conditions

5. 5

   Check for continuity and proper voltage at the A/C compressor clutch connector, as well as the ECM/LCU power supply and ground connections

6. 6

   Inspect the high and low-pressure switches, as malfunctions here can indirectly shut down the compressor

1. 1

   Address preliminary findings

   Rectify any issues found during initial checks, such as replacing blown fuses, cleaning a dirty condenser, or securing loose connections.

2. 2

   Test compressor clutch

   Carefully apply 12V directly to the A/C compressor clutch connector. If the clutch does not engage, it is likely faulty and requires replacement.

3. 3

   Inspect wiring harness

   If the clutch engages with direct power, meticulously inspect the wiring harness between the LCU and the compressor for breaks, chafing, or short circuits. Pay special attention to lead 0732.

4. 4

   Replace Left Control Unit

   If the wiring and compressor clutch are confirmed to be in good working order, the fault likely lies within the CLIMATRAK compressor driver inside the Left Control Unit. Replace the LCU.