Massey Ferguson AC26 – Air Conditioning Control Module: Engine water temperature error

The Air Conditioning system is not receiving valid engine coolant temperature data over the CAN BUS network. When this fault occurs, the system will consider the last valid temperature value received within a 10-second window. If no valid CAN message is received during this time, the system defaults to a fallback value of 90°C to keep the climate control operating in a degraded mode.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• MF 7600 Series
• MF 8600 Series
• 8670
• 8690
• Dyna-4
• Dyna-6
• Dyna-VT (ML260)

1. 1

   Check for Engine ECU Faults: Use a diagnostic tool to check if the Engine ECU is logging its own coolant temperature sensor faults (e.g., E 110 series codes).

2. 2

   Inspect the X440 Connector: Locate the Air Conditioning Control Module and inspect the yellow connector (X440) for loose pins, moisture, or corrosion.

3. 3

   Test CAN BUS Integrity: Verify the continuity of the CAN BUS communication lines between the Engine ECU and the AC Control Module.

4. 4

   Test the Coolant Temperature Sensor: Verify that the engine coolant temperature sensor is reading correctly and that its wiring harness to the Engine ECU is intact.

1. 1

   Connect Diagnostic Tool

   Hook up the AGCO Electronic Diagnostic Tool (EDT) to the tractor's diagnostic port to confirm the AC26 code and check for concurrent engine codes.

2. 2

   Resolve Engine Sensor Issues First

   If the Engine ECU is reporting a faulty coolant temperature sensor, replace the sensor and repair any damaged wiring on the engine harness. If the Engine ECU doesn't know the temperature, it cannot send it to the AC module.

3. 3

   Clean and Reseat Connectors

   Disconnect the X440 yellow connector at the Air Conditioning Control Module. Clean the contacts with electrical contact cleaner, check for pushed-back pins, and securely reconnect it.

4. 4

   Repair CAN BUS Wiring

   If testing reveals an open or short circuit in the CAN network between the Engine ECU and the AC module, repair or replace the affected section of the cab/engine wiring harness.

5. 5

   Replace the AC Module (if necessary)

   If the engine sensor is working, the CAN BUS is intact, and the Engine ECU is successfully broadcasting the temperature data but the AC module still fails to read it, the Air Conditioning Control Module itself has failed internally and must be replaced.

6. 6

   Clear Codes and Test

   Clear the fault codes using the diagnostic tool. Run the tractor and monitor the AC system to ensure it is receiving live temperature data and no longer defaulting to 90°C.