Massey Ferguson 10.00.27 – Air Conditioning Module (AIRCON): Issue With Signal To Left Cab Fan Speed Controller (AIRCON)

The signal from the left cab fan speed controller (also referred to as fan speed controller no. 1) is outside of its normal operating range, or the system is detecting a return error. This typically points to a failure in the blower motor resistor, a faulty fan speed switch, or a wiring issue preventing the module from reading the correct voltage/resistance.

• 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
• 8600 series

1. 1

   Verify the code: Access the diagnostic system through the tractor's display panel to confirm 10.00.27 is active.

2. 2

   Test the fan switch: Turn the AC/Heater fan control switch through all its positions (Low, Medium, High). If the fan only works on 'High' but not on lower speeds, the blower motor resistor is almost certainly blown.

3. 3

   Inspect wiring and connectors: Check the wiring harness leading to the left cab fan speed controller (blower motor resistor) and the air conditioning control module. Look for melted connectors, corrosion, or chafed wires.

4. 4

   Check voltage: Use a multimeter to verify that voltage is passing from the blower switch to the thermostatic switch and down to the resistor.

1. 1

   Disconnect power

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

2. 2

   Locate the component

   Access the left cab fan speed controller (blower motor resistor). Depending on the cab model, this is typically located in the cab roof assembly near the left blower motor, or under the dash panel.

3. 3

   Remove the faulty unit

   Disconnect the electrical wiring harness plug from the resistor. Remove the mounting screws securing the resistor plate to the HVAC housing and pull the unit out.

4. 4

   Inspect the housing

   Check the housing for any melted plastic or debris that may have caused the resistor to overheat.

5. 5

   Install the new part

   Insert the replacement blower motor resistor and secure it with the mounting screws.

6. 6

   Reconnect

   Plug the electrical harness back into the new resistor. Reconnect the negative battery terminal.

7. 7

   Test and clear

   Turn the ignition on and test the fan at all speed settings. Navigate to the tractor's diagnostic menu and clear the stored 10.00.27 fault code.