New Holland 16120 – ACC: Blower Speed Select Potentiometer Open or Shorted to Power

The Air Conditioning Controller (ACC) has detected that the electrical circuit for the blower speed select potentiometer is experiencing an open circuit or is shorted to a power source. This fault prevents the controller from determining the operator's desired fan speed, which directly impairs or disables the proper operation of the cab's heating, ventilation, and air conditioning (HVAC) blower system.

• T7.220
• T7.235
• T7.250
• T7.260
• T7.270
• T8010
• T8020
• T8030
• T8040
• T8050
• CR9040
• CR9060
• CR9070
• T5.115
• T6000
• TL
• TM
• TS
• T4000
• TN

1. 1

   Visually inspect the blower speed control knob and the surrounding HVAC control panel for any visible damage.

2. 2

   Inspect the wiring harness connected to the HVAC control panel for chafing, breaks, or loose connections. On some models, also check key HVAC connections and ground wires located under the operator's seat.

3. 3

   Scan the system for any other active fault codes related to sensors or 5-volt reference circuits, which could indicate a broader electrical issue rather than a single component failure.

4. 4

   Test the potentiometer/switch resistance with a multimeter (battery disconnected). Measure the resistance between the two outer terminals (should be a fixed value), then measure between the center wiper terminal and outer terminals while slowly rotating the knob; resistance should change smoothly without jumping to zero or Over Limit (OL).

5. 5

   Check for power and ground at the harness connector (battery reconnected, key ON, engine off). Verify the presence of a 5V or 12V reference signal and a solid ground. Absence of these indicates a wiring or ACC issue.

6. 6

   If the switch and wiring test good, inspect the blower motor resistor, which controls fan speed by varying current to the blower motor.

1. 1

   Confirm faulty component

   Based on the diagnostic checks, confirm whether the fault lies with the blower speed select potentiometer/switch, the wiring harness, or the blower motor resistor. The potentiometer is the most likely culprit for this specific code.

2. 2

   Disconnect power

   Turn off the tractor and disconnect the battery to ensure safety during the repair procedure.

3. 3

   Remove the faulty component

   Remove the necessary cab trim or console panels to access the rear of the HVAC control unit. Unplug the electrical connector and remove any retaining nuts or screws to extract the faulty potentiometer or switch.

4. 4

   Install the new part

   Install the replacement potentiometer or switch into the control panel, secure it with the original hardware, and firmly reconnect the electrical connector.

5. 5

   Reassemble and test

   Reassemble the cab panels and trim. Reconnect the battery, turn the key to the 'ON' position, and start the engine. Operate the blower fan through all speed settings to confirm correct functionality, then clear fault code 16120 using the tractor's diagnostic menu or a service tool.