Case IH 119 – Automatic Temperature Controller (ATC): Auto and Manual switch both on

This is an electrical logic error. The system is receiving simultaneous inputs indicating that both the 'Auto' and 'Manual' climate control modes are engaged at the same time. Because these modes are mutually exclusive, the controller flags this as an invalid state and logs the fault.

• STX Steiger
• Steiger series (STX280, STX330, STX430, TJ series)
• Magnum series (180, 190, 210, 215)
• Puma
• Maxxum series
• Axial-Flow (AFX) series (AFX7010, AFX8010, 7120, 7230, 8120, 8230, 9120, 9230)

1. 1

   Inspect the ATC climate control panel in the cab to see if the 'Auto' or 'Manual' buttons are physically stuck, jammed by debris, or collapsed.

2. 2

   Check the wiring harness connecting the ATC switch panel to the ATC controller for pinched wires, chafing, or melted insulation that could cause the signal wires to short together or to power.

3. 3

   Disconnect the switch panel and use a multimeter to test the continuity of the Auto and Manual switches. If either switch reads closed (continuity) when not being pressed, the panel has failed internally.

4. 4

   If the switches and wiring harness test perfectly, check the ATC controller's internal logic board, which may be misinterpreting the inputs.

1. 1

   Power Down

   Turn off the machine and disconnect the negative battery cable to prevent electrical shorts during the repair.

2. 2

   Access the Panel

   Carefully pry or unscrew the trim surrounding the ATC switch panel located in the cab console or headliner (depending on the specific model).

3. 3

   Disconnect and Remove

   Unplug the electrical connectors from the back of the switch panel.

4. 4

   Repair/Replace

   If the diagnostic tests revealed a short in the wiring harness, repair the damaged wires using appropriate splice connectors and heat shrink. If the switch panel failed the continuity test (stuck switches), install a replacement temperature control panel.

5. 5

   Reassembly

   Plug the wiring harness into the new/repaired panel and snap or screw the panel back into the console.

6. 6

   Clear Codes and Test

   Reconnect the battery, turn the key to the ON position, and clear the fault codes from the ATC controller. Test the HVAC system by toggling between Auto and Manual modes to ensure the code does not return and the blower/temperature responds correctly.