Massey Ferguson AC31 – AIRCON Module: Issue With Signal To Left Cab Fan Speed Controller

The climate control system is sending a signal to the left-hand blower motor resistor/speed controller, but the feedback voltage returning to the module is either missing, shorted, or out of the expected parameters.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• 4707
• 4708
• 4709
• 4710
• 5710SL
• 5711SL
• 5712SL
• 5713SL
• 6600 Series
• 7714
• 7715
• 7716
• 7718
• 7719
• 7720
• 7722
• 7724
• 7726
• 8670
• 8690

1. 1

   Gain access to the cab roof where the blower motors and fan adapter modules are located.

2. 2

   Locate the left-hand fan adapter module (X445) and inspect the wiring harness and connectors for signs of melting, corrosion, or loose pins.

3. 3

   Check the return signal wire between the X445 module and the AIRCON control module for continuity, short circuits to ground, or open circuits.

4. 4

   Test the left cab blower motor for excessive current draw, as a failing blower motor pulling too many amps is the most common cause of a burnt-out fan speed controller.

5. 5

   Ensure the voltage supply to the Air Conditioning control module (connectors X439 and X440) is within the normal operating range.

1. 1

   Disconnect Power

   Disconnect the tractor's battery to prevent electrical shorts during the repair.

2. 2

   Remove Cab Roof Panel

   Unbolt and prop up or remove the outer cab roof panel to access the HVAC assembly.

3. 3

   Disconnect the Controller

   Unplug the wiring harness from the faulty left-hand fan adapter module / blower motor resistor (X445).

4. 4

   Remove the Component

   Remove the mounting screws securing the fan speed controller to the HVAC housing and extract it.

5. 5

   Replace Blower Motor (If Necessary)

   If the blower motor failed the amperage draw test during diagnostics, replace it now. Installing a new speed controller on a failing motor will cause the new controller to burn out immediately.

6. 6

   Install New Parts

   Install the new fan speed controller/resistor and secure it with the mounting hardware.

7. 7

   Reconnect Wiring

   Plug the wiring harness back in, ensuring the connector clicks and locks into place.

8. 8

   Reassemble and Test

   Reinstall the cab roof panel. Reconnect the battery, turn the ignition on, and clear the AC31 fault code using the tractor's onboard display or a diagnostic tool. Test the HVAC system across all fan speeds to confirm the left fan operates correctly.