Massey Ferguson AC18 – Air Conditioning Controller / Climate Control Unit (AIRCON): Cab interior temperature sensor Ambient temperature sensor fan fault

Indicates a malfunction in the circuit of the cab's interior temperature sensor (component X69) or a failure of the small ambient temperature sensor fan that draws cabin air across the sensor.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• MF 7600 Series
• 7617
• Dyna-4
• Dyna-6
• Dyna-VT

1. 1

   Listen or feel for the sensor fan to check if it is spinning or clogged with dust and chaff when the key is in the ON position.

2. 2

   Visually inspect the X69 cab interior temperature sensor wiring harness and connector for loose pins, corrosion, or chafed wires.

3. 3

   Perform a voltage and continuity test on the sensor circuit using a multimeter to check for an open circuit or a short to ground or power. Faults typically log if voltage drops below 0.7V or exceeds 4.86V.

1. 1

   Disconnect Power

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

2. 2

   Access the Sensor

   Locate the cab interior temperature sensor (X69) assembly. It is typically mounted behind a small slotted grille on the interior cab trim/headliner.

3. 3

   Clean the Assembly

   If the sensor fan is simply jammed with agricultural dust, carefully blow it out with low-pressure compressed air and re-test.

4. 4

   Replace the Sensor

   If cleaning does not restore fan operation or the thermistor is electrically dead, unplug the electrical connector and unclip the sensor assembly from the trim.

5. 5

   Install the New Part

   Snap the new sensor/fan assembly into place and reconnect the wiring harness.

6. 6

   Clear Codes and Test

   Reconnect the battery, turn the ignition on, clear the stored AC18 fault code via the tractor's diagnostic display, and run the HVAC system to verify the code does not return.