Massey Ferguson 26 – AC Module (AIRCON): No Engine Coolant Temperature Information Received On The CAN BUS To AC Module (AIRCON)

The Air Conditioning control module is failing to receive the expected engine coolant temperature data packets over the CAN bus network from the Engine Control Unit (ECU). The AC system relies on this data to regulate cab temperature, manage the heater valve, and prevent the AC compressor from overloading an overheating engine.

• 7724S
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 7720S
• 7716
• 7718
• 7726
• 7715
• 7616
• 7618
• 7619
• 7626
• 7726S
• 7624
• 7614
• 7718S
• 7620
• 7719
• 7714
• 7716S
• 7622
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 5710SL
• 5711SL
• 5712SL
• 5713SL

1. 1

   Verify Engine ECU Data: Check the tractor's main instrument cluster. If the engine coolant temperature gauge is blank, erratic, or showing an error, the Engine ECU itself does not know the temperature. The fault lies with the Engine Coolant Temperature (ECT) sensor or its direct wiring to the Engine ECU, not the AC module.

2. 2

   Check for Accompanying Codes: Look for other CAN bus communication codes (e.g., Code 10.00.24 "No Engine Speed Information Received" or 10.00.25 "No Vehicle Speed Information Received"). If multiple messages are missing, the CAN bus network to the AC module is physically broken.

3. 3

   Inspect Connectors: Check the multi-pin connectors at the back of the AC Module and the Engine ECU for moisture, corrosion, or backed-out pins (CAN High and CAN Low lines).

1. 1

   Scan the System

   Connect a diagnostic tool (such as Massey Ferguson WinTest) to read all modules. Check the Engine ECU for active faults related to the ECT sensor (e.g., open circuit or short to ground).

2. 2

   Test/Replace the ECT Sensor

   If the Engine ECU is reporting a sensor fault, locate the ECT sensor on the engine block or thermostat housing. Disconnect the pigtail, check for corrosion, and test the sensor's resistance. Replace the sensor if it is out of specification.

3. 3

   Test the CAN Bus

   If the ECT sensor is working perfectly and the dash gauge reads correctly, the issue is isolated to the communication line reaching the AC module. Using a multimeter, probe the CAN High and CAN Low wires between the Engine ECU and the AC Module for continuity and ensure there is no short to ground.

4. 4

   Repair Wiring

   Repair any chafed wires or replace corroded connector pins on the CAN network harness.

5. 5

   Replace the AC Module

   If the wiring is completely intact, the CAN bus has the correct terminating resistance (typically 60 ohms across the network), and the AC module is still failing to read the data, the AC Module's internal CAN transceiver has failed. Replace the AC Module.

6. 6

   Clear Codes

   Clear the fault codes and cycle the ignition to verify Code 26 does not return.