New Holland ATC 127 – ATC (Automatic Temperature Control): High pressure switch (-) input shorted to power

The climate control system has detected a short-to-power condition on the negative (-) side of the air conditioning (A/C) high-pressure switch. Because this switch is normally closed, the short could potentially be present on either wire leading to the switch.

• T8000 Series
• T8010
• T8020
• T8030
• T8040
• T9 Series
• T9000 Series
• T9020
• TG Series
• TG245
• U80
• U80B
• U80C
• W130C
• W170C
• W190C
• W230C
• W300C
• LV80
• LW110.B
• LW130.B
• Magnum 215
• Magnum 245
• Magnum 275
• Magnum 305
• Magnum 335
• Steiger series

1. 1

   Visually inspect the wiring harness and all connectors between the A/C high-pressure switch and the ATC controller for any signs of rubbing, melting, or physical damage.

2. 2

   Perform a voltage test to check for a short: Turn the key switch to the 'ON' position, disconnect the wiring harness connector at the A/C high-pressure switch, and measure the voltage between the negative pin on the harness connector and a known good chassis ground to verify if voltage is improperly present.

1. 1

   Harness Repair

   If your visual inspection or voltage test reveals damage to the connectors or wiring (e.g., a bare wire touching a power source), repair or replace the affected section of the wiring harness.

2. 2

   Clear Codes

   After repairing the wiring, clear all fault codes from the ATC module and run the A/C system to verify the fix.

3. 3

   Controller/Switch Verification

   If no damage to the wiring harness is found and the wiring tests good, the fault lies either internally within the A/C high-pressure switch (stuck/shorted internally) or the ATC controller itself has failed. Replace the high-pressure switch first as it is the most common and cost-effective failure point.