What does it mean?
B1280 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Air Mix Switch Potentiometer Short (High)–Console .
Symptoms
- Cabin temperature stays locked at full hot or full cold whatever the dial is set to
- Automatic climate control ignores the temperature setting and reverts to a default
- Clicking or buzzing from behind the dashboard as the blend servo hunts for a position it cannot confirm
- Blower speed and mode selection still work, only temperature control is lost
- Climate display may flash or show a system fault; engine running is unaffected
Likely causes
- Worn or contaminated wiper track inside the air mix servo potentiometer, giving a permanently high output
- Signal wire shorted to the 5V reference or to battery voltage in the console harness
- Open or high-resistance ground return at the potentiometer, which pushes the signal toward reference voltage
- Corroded or spread terminals in the servo connector behind the centre console
- Blend door binding or a stripped servo gear parking the potentiometer at the end of its travel
- Liquid spillage into the console wiring area
- Failed input stage in the heater/climate control panel
How to fix it
- Read the live air mix potentiometer voltage with a scan tool while sweeping the temperature setting; a value pinned near reference voltage confirms the fault
- Unplug the servo and see whether the signal voltage falls; if it stays high the harness is shorted to a supply
- Inspect the console harness and the servo connector for spread terminals, corrosion and liquid damage
- Measure the 5V reference and the ground return at the servo connector with a multimeter
- Remove the servo and check that the blend door moves freely by hand, freeing any binding linkage
- Replace the air mix servo/potentiometer if its resistance does not sweep smoothly across the full range
- Replace the climate control head only after harness and servo are proven good, then clear codes and let the door positions recalibrate