New Holland ATC 115 – ATC (Automatic Temperature Controller): Evaporator temperature sensor is open or shorted to power

The control module is reading an abnormally high voltage on the sensor circuit. This condition is typically caused by a disconnected sensor plug, a broken wire (open circuit), a wire shorting to a power source, or an internal failure of the sensor itself. The evaporator sensor's job is to monitor the temperature of the A/C evaporator core to prevent it from freezing over; if the sensor fails, the system will usually disable the A/C compressor to prevent damage.

• T8.xxx Series
• T9 Series
• T8040
• TJ Series
• Magnum 235-340 (Series 4)
• MX Magnum
• B90B
• B95C

1. 1

   Locate the evaporator temperature sensor wiring near the HVAC box and check the 2-pin connector to ensure it is securely plugged in and free of corrosion.

2. 2

   Inspect the wiring harness between the ATC module and the sensor for chafing, broken wires (open circuit), or melted insulation that could cause a short to a 12V power source.

3. 3

   Disconnect the sensor and use a digital multimeter to measure the resistance across the sensor's pins. An infinite reading (OL) indicates an internal open circuit, meaning the sensor is dead and must be replaced.

1. 1

   Access the HVAC Unit

   Remove the necessary cab interior panels or roof cap to access the main HVAC evaporator housing.

2. 2

   Locate the Sensor

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

3. 3

   Remove the Old Sensor

   Disconnect the electrical connector. Carefully pull the sensor probe straight out of the evaporator core fins (or unclip it from its sensor holder).

4. 4

   Install the New Sensor

   Insert the new sensor probe into the exact same location/depth in the evaporator fins to ensure accurate temperature readings.

5. 5

   Reassemble and Clear Codes

   Reconnect the wiring harness, reassemble the cab panels, and turn on the machine. Toggle the ATC switch to OFF and then back to the operational mode to reset the system and clear the fault code. Verify that the A/C compressor engages and blows cold air.