Massey Ferguson 10.01.31 – AIRCON: Issue With Signal To Left Cab Fan Speed Controller

The system has detected that the signal from the fan speed controller (potentiometer) is outside of its normal operating range, or there is a 'fan speed controller no. 1 return error'. This means the control module is receiving an implausible voltage or resistance reading from the left-side blower control circuit, which defaults the system or disables the left fan to prevent electrical damage.

• 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 between the AIRCON module, the left cab fan speed switch (potentiometer), and the blower motor resistor for chafed wires, melted connector pins, or corrosion.

2. 2

   Use a multimeter to test the left fan speed switch (potentiometer) to verify that the resistance changes smoothly and continuously as the dial is turned.

3. 3

   Check the blower motor resistor for continuity to ensure it is not burnt out, which causes an open circuit on specific fan speed settings.

4. 4

   Ensure the left blower motor spins freely. A seized or failing blower motor can draw excessive amperage, burning out the resistor or damaging the controller circuit.

1. 1

   Disconnect Power

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

2. 2

   Access the Climate Components

   Remove the cab roof liner or the specific access panel for the left-side HVAC blower assembly.

3. 3

   Inspect and Replace the Resistor

   Locate the blower motor resistor (usually mounted directly in the airflow path of the blower housing to keep it cool). Disconnect the electrical plug. Remove the mounting screws, pull out the old resistor, and install the new one.

4. 4

   Inspect and Replace the Switch (if necessary)

   If diagnostics pointed to the potentiometer, carefully pry out the climate control panel on the dash/console. Disconnect the harness from the back of the fan speed switch, unclip the switch from the bezel, and snap the new switch into place.

5. 5

   Reassembly

   Reconnect all electrical plugs securely. Reinstall the roof liner or access panels.

6. 6

   Testing

   Reconnect the battery. Turn the ignition to the ON position and cycle the left fan through all speed settings. Verify that the fan operates correctly on every speed and that the 10.01.31 fault code changes to an inactive state or clears from the dash display.