Massey Ferguson 9 – Air Conditioning / Climate Control Module (AIRCON): Evaporator temperature sensor fault - Sensor open

An open circuit in the A/C evaporator temperature sensor circuit, indicating a broken wire, a disconnected plug, or a completely failed sensor. The system automatically turns off the air conditioning compressor to prevent the evaporator core from freezing over.

• 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
• 8600 Series
• 8670
• 8690
• 7600 Series
• 3000 Series
• 4200 Series
• 4300 Series
• 6100 Series
• 6200 Series
• 6400 Series
• 6465
• 6480
• 8700S Series
• 8727S
• 8730S

1. 1

   Access the HVAC unit and visually inspect the wiring harness connecting the AIRCON module to the evaporator temperature sensor for disconnected plugs, chewed wires (rodent damage), or chafing.

2. 2

   Disconnect the sensor from the harness and use a digital multimeter to measure the resistance across the sensor's two terminals. If the multimeter reads 'OL' (Open Loop) or infinite resistance, the sensor has failed internally.

3. 3

   If the sensor tests within normal resistance specifications, test for continuity on the harness between the sensor connector and the AIRCON control module pins to locate the break.

1. 1

   Power Down

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

2. 2

   Access the HVAC Unit

   Remove the inner roof liner/headliner or the specific HVAC access panels to expose the air conditioning assembly.

3. 3

   Locate the Sensor

   Find the evaporator temperature sensor. It is a probe-style sensor inserted directly into the aluminum fins of the A/C evaporator core.

4. 4

   Remove the Faulty Sensor

   Unplug the 2-pin electrical connector. Carefully pull the old sensor probe straight out of the evaporator fins.

5. 5

   Install the New Sensor

   Gently insert the new temperature sensor probe into the exact same location in the evaporator core. Ensure it is seated deeply enough to get an accurate temperature reading of the core to prevent freezing.

6. 6

   Reassembly

   Reconnect the electrical harness. Reinstall the cab roof liner and access panels.

7. 7

   Test

   Reconnect the battery, start the tractor, and turn on the A/C. Verify that the fault code has cleared and that the A/C compressor clutch engages to provide cold air.