Massey Ferguson 17 – Air Conditioning Panel Module (AIRCON): Input error from fan speed potentiometer

The electrical signal coming from the fan speed dial (potentiometer) is outside of its normal operating range, indicating either an open circuit, a short circuit, or a failed internal resistor. When this code is triggered, the system enters a failsafe mode and controls the fan speed automatically.

• 7724S
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 7720S
• 7716
• 7718
• 7726
• 7715
• 7616
• 7618
• 7619
• 7626
• 7726S
• 7624
• 7614
• 7718S
• 7620
• 7719
• 7714
• 7716S
• 7622
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724
• 8600 Series
• 8650
• 8660
• 8670
• 8680
• 8690
• 4700 Series
• 5700 Series
• 6700 Series
• 7600 Series
• 7700 Series
• 5400
• 6400
• 7400

1. 1

   Turn the fan speed dial manually to check for physical binding, looseness, or lack of resistance which indicates a broken internal potentiometer shaft.

2. 2

   Remove the AC control panel and inspect the wiring harness connectors at the rear of the AIRCON module for backed-out pins, corrosion, or chafed wires that could cause an open or short circuit to ground.

3. 3

   Using a multimeter or the AGCO Electronic Diagnostic Tool (EDT), monitor the live voltage/resistance sweep of the fan speed potentiometer. Check if the signal drops out entirely, spikes out of range, or reads a constant short to ground while turning the dial.

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the tractor's battery isolator switch to prevent electrical damage.

2. 2

   Access the Panel

   Carefully pry away the plastic trim/bezel surrounding the Air Conditioning Control Panel in the cab console or headliner (depending on the specific model).

3. 3

   Remove the Module

   Unscrew the retaining fasteners holding the AC panel in place. Pull the panel forward and disconnect the main electrical harness connectors from the rear.

4. 4

   Replace the Component

   If the potentiometer is modular: Pull the fan speed knob off the front of the panel. Unbolt the retaining nut holding the potentiometer to the circuit board, desolder/disconnect the old potentiometer, and install the replacement switch. If the panel is a sealed unit: You will need to replace the entire Air Conditioning Control Panel assembly.

5. 5

   Reassembly

   Reconnect the wiring harnesses to the rear of the panel and secure it back into the console. Snap the trim bezel back into place.

6. 6

   Testing

   Reconnect the battery, turn the ignition on, and test the fan speed dial across all speeds. Verify that manual control is restored and use a diagnostic tool to clear the inactive fault code.