New Holland ATC 131 – ATC (Automatic Temperature Control) / HVAC Controller: Low pressure switch (+) input shorted to ground.

The ATC module detects that the positive (+) signal wire coming from the low-pressure switch is shorted directly to the chassis ground, disabling the A/C system to protect the compressor.

• T6 Series
• T7 Series
• T8 Series
• T9 Series
• TG Series
• TJ Series
• CR Series
• CR9040
• CR9060
• CX Series
• CX8070
• CX8080
• FR Series
• HW/H8000 Series

1. 1

   Check refrigerant levels to verify the system has the correct static pressure

2. 2

   Inspect the wiring harness leading to the low-pressure switch for chafed insulation, pinched wires, or melted loom

3. 3

   Disconnect the electrical pigtail from the switch and test for continuity between the (+) signal wire and chassis ground

4. 4

   Test the switch terminals for an internal short to its own metal housing

1. 1

   Power Down

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

2. 2

   Harness Repair

   If a short was found in the wiring during diagnostics, splice and heat-shrink the damaged section of the (+) input wire.

3. 3

   Remove the Faulty Switch

   If the switch itself has failed internally, disconnect its weather-sealed electrical connector.

4. 4

   Unthread the Switch

   Unscrew the low-pressure switch from the A/C service port.

5. 5

   Install the New Switch

   Thread the new OEM pressure switch onto the 10mm metric fitting and tighten securely.

6. 6

   Reconnect

   Plug the electrical connector back into the new switch.

7. 7

   Clear Codes and Test

   Reconnect the battery, turn the key on, and use the tractor's diagnostic menu to clear the ATC 131 code. Start the machine and test the A/C system to ensure the compressor engages and the cab cools properly.