Massey Ferguson 18 – Air Conditioning Controller (AIRCON): Ambient temperature sensor fan fault - The fan does not turn

In automatic climate control systems, the cab interior temperature sensor utilizes a tiny built-in aspirator fan to constantly draw cabin air across the thermistor (temperature probe) for accurate readings. This fault code is logged when the controller detects that this small fan has seized, is blocked by debris, or has suffered an electrical failure.

• 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
• 7600 Series
• 6700 Series
• Models equipped with Dyna-4, Dyna-6, and Dyna-VT transmissions

1. 1

   Locate the cab interior temperature sensor (connector X69, typically mounted on the right side of the cab near the fuse panel or B-pillar) and inspect the sensor's grille for heavy dust, chaff, or debris that might be physically jamming the tiny fan blade.

2. 2

   Disconnect the sensor and inspect the wiring harness and connector for corrosion, backed-out pins, or broken wires.

3. 3

   Turn the ignition on and use a multimeter to verify that the sensor is receiving the correct reference voltage and ground from the AIRCON controller.

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the battery isolator to prevent electrical shorts.

2. 2

   Access the Sensor

   Locate the cab temperature sensor inside the cabin. Carefully pry off or unscrew the plastic trim/housing securing the sensor.

3. 3

   Disconnect

   Unplug the electrical connector (X69) from the back of the sensor assembly.

4. 4

   Remove

   Unclip or unscrew the faulty sensor from its mounting bracket.

5. 5

   Install

   Snap the new cab temperature sensor into place and reconnect the wiring harness.

6. 6

   Reassemble

   Reinstall the interior trim panels.

7. 7

   Clear Codes

   Reconnect the battery. Turn the ignition on and use the tractor's onboard diagnostic screen or the AGCO Electronic Diagnostic Tool (EDT) to clear the AC18 fault code. Test the A/C system to ensure the code does not return.