Massey Ferguson 2 – AIRCON: Air Conditioning Vent Temperature Sensor Short Circuit

The electrical signal from the sensor to the controller is bypassing its normal resistance path (reading near zero ohms). Because the controller cannot determine the actual temperature of the air coming out of the vents, it defaults to a fail-safe mode. The automatic climate control is disabled, and the A/C compressor and heater water valve must be controlled manually by the operator.

• 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
• Global Series / Tier 4 models
• 4700 series
• 5600 series
• 5700 series
• 6700 series
• 7600 series
• 7700 series
• 4707-4710
• 5710SL-5713SL
• 7614-7626
• 7714-7726S

1. 1

   Inspect the wiring harness leading from the AIRCON module to the vent/mixed air temperature sensor for pinched wires, rubbed-through insulation, or melted sections.

2. 2

   Disconnect the sensor and inspect the plug for moisture, corrosion, or bent pins bridging the connection.

3. 3

   Perform a sensor resistance test with a multimeter (sensor disconnected). A reading near zero ohms indicates the sensor is internally shorted.

4. 4

   Perform a circuit test on the wiring harness for continuity between the two wires (disconnected from both sensor and AIRCON module). Continuity indicates a short in the harness.

1. 1

   Power Down

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

2. 2

   Access the HVAC Unit

   Access the HVAC plenum/ducting, which is typically located under the cab roof or behind the cab interior panels depending on the specific tractor model.

3. 3

   Locate the Sensor

   Find the vent/mixed air temperature sensor protruding into the air duct.

4. 4

   Remove the Sensor

   Disconnect the electrical pigtail. Remove the sensor (usually secured by a twist-lock mechanism or a small retaining screw).

5. 5

   Install the New Part

   Insert the replacement sensor into the duct and secure it. Reconnect the electrical harness.

6. 6

   Reassembly & Clearing Codes

   Reassemble the cab panels. Reconnect the battery. Turn the ignition on and use the AGCO Electronic Diagnostic Tool (EDT) to clear the logged fault code.

7. 7

   Test

   Run the tractor and set the climate control to "Auto" to verify that the blend doors and A/C compressor now regulate the cab temperature automatically.