Massey Ferguson 10.03.31 – Air Conditioning Module (AIRCON): Issue With Signal To Left Cab Fan Speed Controller (AIRCON)

The signal from the left cab fan speed controller (or fan speed potentiometer) is outside of its normal operating range. The system registers this as a 'Fan speed controller no. 1 return error,' which typically results in the left blower motor failing to operate, operating only on a single speed (usually high), or functioning intermittently.

• 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
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626

1. 1

   Inspect the wiring harness leading to the left cab fan speed controller (blower motor resistor) for any physical damage, breaks, or melted insulation.

2. 2

   Use a multimeter to verify that proper voltage is reaching the controller to rule out a blown fuse or broken wire upstream.

3. 3

   Test the signal from the fan speed potentiometer to check if the resistor pack has short-circuited to earth or has an open circuit.

4. 4

   Ensure the left blower motor itself spins freely, as a seizing blower motor draws excessive amperage and can burn out the fan speed controller.

1. 1

   Disconnect Power

   Turn off the tractor ignition and disconnect the battery to prevent electrical shorts.

2. 2

   Access the HVAC Unit

   The blower motors and resistors are typically located in the cab roof canopy. Remove the inner roof liner or the exterior roof access panel, depending on your specific cab configuration.

3. 3

   Locate the Controller

   Locate the left cab fan speed controller (blower motor resistor), which will be mounted near or directly on the left blower motor housing to utilize the airflow for cooling.

4. 4

   Remove the Faulty Part

   Disconnect the electrical connector plug from the controller. Remove the retaining screws and pull the controller out of the housing.

5. 5

   Install the New Part

   Insert the replacement fan speed controller, secure it with the retaining screws, and plug the electrical connector back in.

6. 6

   Test the System

   Reconnect the battery and turn the ignition on. Test the air conditioning fan on all speed settings to ensure the left fan responds correctly.

7. 7

   Clear Codes

   Reassemble the cab roof. Use the AGCO Electronic Diagnostic Tool (EDT) to clear the inactive 10.03.31 fault code from the AIRCON module memory.