Body, generic

B0168 HVAC Air Mix Door Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

B0168 shows up neither in the publicly available J2012 lists nor, with this meaning, in public carmaker documents; air mix door circuits have the codes B0258 and B0263. The air mix or blend door divides the airflow, sending part across the heater core and part past it, and so sets outlet temperature. A performance fault means it does not reach or hold its target. An older Japanese patent (CA1266779A) shows how sensitive this is: in the door range where a small movement changes air temperature a lot, the motor gets lower voltage to stop the door hunting. In US5529112A the temperature door motor runs into its end stop and stays stalled there. GM's Global A climate control drives this door with a stepper motor and logs it under B0408.

Likely causes

Blend door shaft or lever broken or slipping on the actuator
Air mix actuator gear worn or motor weak
Foreign object or debris in the HVAC case blocking the door

Symptoms

  • Outlet air stays hot or cold regardless of the temperature setting
  • Temperature swings or clicking behind the dash

Repair estimate

DifficultyMediumDIY possible
Parts and labour€60–800
Time0.5–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

air mix door actuatorhvac control module

Related codes

B0258B0263

References: patents.google.com, patents.google.com, saabwisonline.com.