New Holland ATC 130 – ATC (Automatic Temperature Control) Controller: Low pressure switch (+) input shorted to power

The system detects that the positive signal wire coming from the air conditioning (A/C) low-pressure switch is receiving unintended voltage (shorted to a power supply). This disrupts the safety signal designed to shut down the A/C compressor if system pressure drops too low.

• T5 Series
• T6 Series
• T7 Series
• T8 Series
• T9 Series
• TG Series
• TJ Series
• 8000 Series
• CR Series (CR9040, CR9090)
• CX Series (CX8070, CX8090)
• FR Series (FR600, FR850)
• L-Series skid steers
• HW/H-Series windrowers
• 8670
• 8770
• 8870
• 8970
• 8260
• 7740

1. 1

   Visual Wiring Inspection: Inspect the wiring harness and all connectors between the A/C low-pressure switch and the ATC controller. Look for chafed wire insulation, pinched wires, or areas where the harness might be rubbing against a hot or moving engine component, exposing the wire to a 12V power source.

2. 2

   Connector Check: Disconnect the plug at the low-pressure switch. Check for water intrusion, corrosion, or melted pins that could be bridging the power and signal circuits.

3. 3

   Multimeter Voltage Test: With the switch disconnected and the key ON, use a multimeter to probe the signal wire going back to the ATC module. If it shows 12V (or reference voltage higher than specified), the short is in the harness.

4. 4

   Controller Check: If the wiring harness tests perfectly fine with no shorts, the ATC controller itself may have suffered an internal failure and is bleeding voltage into the circuit.

1. 1

   Power Down

   Turn off the machine and remove the key.

2. 2

   Locate the Switch

   Locate the A/C low-pressure switch, which is threaded into the low-side A/C refrigerant line (usually near the receiver drier or firewall).

3. 3

   Repair Wiring (If Applicable)

   If your diagnostic tests revealed a short in the harness, splice and repair the damaged section of the wire using weather-sealed heat-shrink connectors. Wrap the repaired section in protective loom.

4. 4

   Replace the Switch (If Applicable)

   If the wiring is intact but the switch is internally shorted: Unplug the electrical connector. Unscrew the low-pressure switch from the A/C line slowly to ensure the Schrader valve is holding (if refrigerant aggressively leaks, stop and have the system professionally evacuated). Thread the new OEM switch onto the fitting and tighten to spec. Reconnect the electrical harness.

5. 5

   Clear Codes and Test

   Turn the key ON, navigate to the tractor's diagnostic menu (or use a CNH Electronic Service Tool), and clear the ATC 130 fault code. Start the machine and turn the A/C on to verify the compressor engages and the code does not return.