Massey Ferguson 32 – AIRCON: Issue With Signal To Right Cab Fan Speed Controller

The return signal from the right-hand cab fan speed controller (blower motor resistor) is outside of its normal operating range. The control module is not receiving the expected voltage feedback, indicating a failure in the resistor itself, a wiring issue, or a problem with the blower motor. When this component fails, the right cab fan typically only works on high speed or stops blowing entirely.

• 7724S
• Interim Tier 4 (2012-2015)
• 7722S
• 7722
• 7615
• 7720S
• 7716
• 7718
• 7726
• 7715
• 7616
• 7618
• 7619
• 7626
• 7624
• 7726S
• 7614
• 7718S
• 7620
• 7719
• 7714
• 7716S
• 7622
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724
• 4700 Series
• 4707
• 4708
• 4709
• 4710
• 5600 Series
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 5700 Series
• 5709
• 5710
• 5711
• 5712
• 5713
• 6400 Series
• 6445
• 6455
• 6460
• 6465
• 6470
• 6475
• 6480
• 6485
• 6490
• 6495
• 6497
• 6499
• 6600 Series
• 6613
• 6614
• 6615
• 6616
• 6700 Series
• 6712
• 6713
• 6714
• 6715
• 6716
• 6718
• 7400 Series
• 7465
• 7475
• 7480
• 7485
• 7490
• 7495
• 7497
• 7499
• 7600 Series
• 7700 Series
• 8400 Series
• 8450
• 8460
• 8470
• 8480
• 8600 Series

1. 1

   Verify the Symptom: Check the operation of the right-hand cab fan. If it only blows on the highest speed setting or does not turn on at all, the blower resistor has likely failed.

2. 2

   Inspect Wiring and Connectors: Because the resistor generates significant heat during electrical resistance operation, the wiring harness and plug-in connector are prone to melting or corrosion from cab humidity. Inspect the connector for burnt pins before assuming the resistor is the only faulty part.

3. 3

   Check the Blower Motor: Ensure the right blower motor spins freely. A failing blower motor that draws excessive amperage can cause the new resistor to burn out prematurely.

4. 4

   Check Battery Voltage: Ensure the tractor's battery is fully charged (around 12.6V), as low voltage can cause the AIRCON module to log false undervoltage or signal errors.

1. 1

   Safety First

   Turn off the tractor and disconnect the battery. If the fan has been running, allow the HVAC system to cool down, as the resistor gets extremely hot during operation.

2. 2

   Locate the Resistor

   Access the HVAC unit (typically located in the cab roof). The resistor is mounted near the blower motor, where the system uses airflow to help keep the component cool.

3. 3

   Disconnect

   Unplug the electrical connector from the resistor.

4. 4

   Remove

   Remove the mounting screws holding the old resistor in place and pull it out of the housing.

5. 5

   Clean and Inspect

   Clean the mounting area to ensure proper ventilation around the new resistor to prevent overheating.

6. 6

   Install

   Insert the new blower resistor, secure it with the screws, and plug the connector back in.

7. 7

   Test

   Reconnect the battery, turn on the ignition, and test the right cab fan across all speed settings to confirm the repair.