Case IH 518502-05 - BCM – BCM: Air conditioner clutch solenoid driver - open circuit

The control module is commanding the A/C compressor clutch to engage, but it does not detect the expected electrical current flowing through the circuit. This typically points to a broken wire, a disconnected plug, a blown fuse, or an internally failed (open) A/C clutch coil.

• MAGNUM AFS Connect
• Magnum 400 AFS Connect, Tier 3
• Steiger/Quadtrac AFS Connect

1. 1

   Visually inspect the electrical connector directly at the A/C compressor clutch solenoid. Ensure it is securely plugged in, the locking tab is intact, and the pins are free of dirt and corrosion.

2. 2

   Inspect the tractor's power distribution box. Locate and test the 'Air conditioner clutch solenoid' fuse and the A/C clutch relay.

3. 3

   Unplug the A/C compressor clutch and use a multimeter to measure the resistance across the clutch coil pins. An infinite resistance reading (OL) indicates the internal electromagnetic coil is broken/open.

4. 4

   If the coil tests good, use a multimeter to check for continuity in the wiring harness between the BCM output pin and the A/C clutch solenoid connector. Look for chafed, pinched, or broken wires along the engine block routing.

5. 5

   With the engine running and the A/C commanded ON in the cab, verify if battery voltage is reaching the clutch connector.

1. 1

   Safety First

   Turn off the tractor and disconnect the negative battery cable before servicing electrical components to prevent accidental short circuits.

2. 2

   Repair Wiring

   If the diagnostic checks revealed a broken wire or damaged connector between the BCM and the A/C compressor, repair the wiring harness using proper weather-sealed splicing techniques or replace the damaged connector pigtail.

3. 3

   Replace Relay/Fuse

   If the A/C clutch relay or fuse is blown, replace it with a new one of the exact same amperage rating. Note: A blown fuse often indicates a short circuit occurred prior to the open circuit, so inspect the wiring carefully.

4. 4

   Replace A/C Clutch

   If the A/C clutch coil tested open (infinite resistance): Remove the serpentine drive belt, remove the center retaining bolt on the A/C compressor clutch hub, use a clutch puller tool to remove the faulty clutch assembly, and install the new A/C clutch assembly setting the proper air gap. (Note: On some compressor models, the entire A/C compressor must be replaced and the system recharged).

5. 5

   Clear Codes

   Reconnect the battery, turn the key on, and use the AFS Connect display or a diagnostic scan tool to clear the 518502-05 fault code.

6. 6

   Test Operation

   Start the engine, turn on the A/C, and verify that the compressor clutch engages and the cab cools properly.