Case IH 130 – ATC (Automatic Temperature Control): Low pressure switch (+) input shorted to power

The system has detected a short to a power source on the positive circuit of the air conditioning (A/C) low-pressure switch. This switch is a safety device designed to monitor refrigerant pressure and prevent the A/C compressor clutch from engaging if the system pressure drops too low (which could cause catastrophic compressor damage).

• STX Steiger
• Magnum 180
• Magnum 200
• Magnum 215
• Magnum 220
• Magnum 235
• Magnum 240
• Magnum 245
• Magnum 250
• Magnum 275
• Magnum 305
• Magnum 335
• Magnum 340
• Magnum 380
• Steiger 435
• Steiger 500
• Steiger 550
• Puma 125
• Puma 130
• Puma 145
• Puma 160
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225
• Maxxum 110
• Maxxum 115
• Maxxum 120
• Maxxum 125
• Maxxum 130
• Maxxum 140
• Maxxum 145
• Maxxum 150
• MXM120
• MXM130
• MXM140
• MXM155
• MXM175
• MXM190
• Farmall 90
• Farmall 95
• JX55 through JX95
• Combine 2144
• Combine 2166
• Combine 2188
• Combine 2344
• Combine 2366
• Combine 2388
• Combine 7230
• Combine 7240

1. 1

   Locate the low-pressure switch on the A/C refrigerant lines. Visually inspect the wiring harness and all connectors between the low-pressure switch and the ATC controller.

2. 2

   Look for chafed wires, melted insulation, or pinched harnesses that could cause the positive wire to short against a 12V power source.

3. 3

   Disconnect the switch and check for corrosion, moisture, or bent pins inside the connector.

4. 4

   With the key ON, test the harness side of the connector to verify if voltage is bleeding into the signal wire inappropriately.

1. 1

   Repair Wiring

   If damage to the connectors or wiring is found during the visual inspection, repair the damaged section of the harness or replace the pigtail connector.

2. 2

   Replace the Switch

   If the wiring tests perfectly fine, the switch itself may have failed internally.

3. 3

   Evacuate/Recover Refrigerant

   Check if the switch is mounted on a Schrader valve. If it is, it can be unscrewed without losing refrigerant. If it is not, you must safely recover the A/C refrigerant using an A/C machine before removing the switch.

4. 4

   Install New Switch

   Thread the new low-pressure switch onto the fitting (Thread Size: 7/16" - 20 UNF).

5. 5

   Recharge and Clear Codes

   If the system was evacuated, pull a vacuum and recharge the A/C system to factory specifications. Clear the ATC 130 fault code from the diagnostic menu and test the A/C clutch engagement.