Massey Ferguson 10.X.24 – Air Conditioning Control Module (AIRCON): No Engine Speed Information Received On The CAN BUS To AC Module (AIRCON)

The Air Conditioning (AC) control module relies on engine speed data broadcasted over the tractor's CAN bus network by the Engine Control Unit (ECU). This data is required to safely engage the AC compressor. When the AC module stops receiving this specific CAN message, it logs this code and typically disables the air conditioning system to protect the compressor.

• 7724S
• 5712SL
• 7722
• 7722S
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7726S
• 5711SL
• 7718S
• 7719
• 7714
• 7716S
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724
• 8600 Series
• 8650
• 8660
• 8670
• 8680
• 8690
• 7600 Series
• 7700 Series
• 4700 Series
• 5700 Series
• 6700 Series

1. 1

   Verify Engine Speed Sensor Operation: Check the tractor's dashboard tachometer. If the tachometer is reading 0 RPM while the engine is running, or if the Engine ECU is logging its own speed sensor faults, the root cause is a faulty engine speed sensor, not the AC module.

2. 2

   Check for Global CAN Bus Faults: If multiple modules are throwing CAN bus communication errors, the issue is a global CAN network failure (e.g., a shorted wire or failed terminating resistor) rather than an isolated AC module issue.

3. 3

   Inspect AC Module Connectors: Inspect the AC Control Module connectors (often designated as X439 Blue and X440 Yellow in MF wiring diagrams) for moisture, corrosion, or backed-out pins.

4. 4

   Test CAN Bus Integrity: With the battery disconnected, measure the resistance across the CAN High and CAN Low pins at the AC module connector. A healthy CAN bus should read approximately 60 ohms.

1. 1

   Safety First

   Turn off the tractor, remove the key, and disconnect the negative battery terminal.

2. 2

   Access the AC Module

   Remove the necessary cab roof panels or console trim to access the Air Conditioning Control Module.

3. 3

   Clean and Reseat Connections

   Disconnect the wiring harnesses to the AC module. Spray the pins and connectors with a high-quality electrical contact cleaner. Ensure no pins are bent, and firmly reconnect the harnesses.

4. 4

   Wiring Harness Repair

   If the CAN bus resistance test failed, trace the twisted-pair CAN wires from the cab down to the Engine ECU. Look for pinch points, chafing, or rodent damage. Repair any broken wires using proper solder and heat-shrink tubing.

5. 5

   Component Replacement

   If the wiring is intact and a diagnostic tool (like the Massey Ferguson EDT) confirms the Engine ECU is broadcasting the engine speed, the AC Control Module has an internal CAN transceiver failure and must be replaced. If the tachometer is dead and the ECU is not reading engine speed, replace the Engine Speed Sensor on the engine block.

6. 6

   Clear Codes

   Reconnect the battery, start the tractor, and use the diagnostic menu or EDT tool to clear the fault codes. Verify the AC compressor clutch engages.