B0423 on GMC
Air Temperature Control (Passenger/Right Side) Circuit Performance
B0423 on GMC vehicles indicates air temperature control (passenger/right side) circuit performance. Au7o has documented this code across 3 GMC models — most commonly on Sierra 3500HD, Terrain, Yukon. B0423 is an HVAC (climate control) code indicating a problem with the right/passenger-side air temperature control circuit, typically the temperature blend-door actuator that mixes hot and cold air. The climate control module is not getting the expected feedback position from this actuator, so the cabin temperature on that side may not match the setting. This is a comfort/convenience fault, not a safety issue. Typical repair costs on GMC range from $60 to $650, depending on the specific model and root cause.
Common Causes of B0423
- •Faulty passenger-side temperature blend-door actuator
- •Stuck or broken blend door
- •Open, shorted, or chafed actuator wiring
- •Corroded or loose actuator connector
- •Faulty HVAC control module
- •Poor ground to the actuator
- •Mechanical obstruction binding the blend door
B0423 on GMC by Model
GMC Sierra 3500HD(1 issue)
- Blend door actuator failure causing temperature/airflow control problems2007-2019
Sierra 3500HD owners report clicking/ticking behind the dash and inability to control cabin temperature due to HVAC blend door or mode door actuator failures. GM service bulletins and owner reports describe stripped actuator gears or actuator motor failures that can leave the truck stuck on hot, cold, defrost, or a single vent mode.
GMC Terrain(1 issue)
- HVAC Blend Door Actuator Failure (Clicking Noise, No Temperature Control)2010-2017
The HVAC blend/mode-door actuators fail as their internal plastic gears strip, producing a repetitive clicking or knocking sound from behind the dash and causing loss of temperature or airflow control. On dual-zone systems one side commonly blows hot while the other blows cold, or the system sticks on one temperature. A click/pop typically means a stripped gear requiring replacement.
GMC Yukon(1 issue)
- HVAC Blend Door Actuator Failure (Clicking Behind Dash)2007-2014
The small electric blend-door actuators that control temperature and air-flow direction strip their internal plastic gears, producing a repetitive tapping/clicking noise from behind the radio or glovebox and causing the HVAC to blow the wrong temperature (e.g., stuck cold on the passenger side) or fail to change modes. It is one of the most common comfort complaints on the GMT900 Yukon and often affects more than one of the several actuators over the vehicle's life.
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View B0423 across all makes →Frequently Asked Questions
What does B0423 mean on GMC?▼
B0423 stands for "Air Temperature Control (Passenger/Right Side) Circuit Performance." B0423 is an HVAC (climate control) code indicating a problem with the right/passenger-side air temperature control circuit, typically the temperature blend-door actuator that mixes hot and cold air. The climate control module is not getting the expected feedback position from this actuator, so the cabin temperature on that side may not match the setting. This is a comfort/convenience fault, not a safety issue. On GMC specifically, this code is documented across 3 models.
What causes B0423 on GMC vehicles?▼
Common causes on GMC: Faulty passenger-side temperature blend-door actuator, Stuck or broken blend door, Open, shorted, or chafed actuator wiring, Corroded or loose actuator connector, Faulty HVAC control module. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix B0423 on a GMC?▼
Repair costs on GMC range from $60 to $650, depending on the specific model and root cause.
Which GMC models have B0423 documented?▼
Au7o has documented B0423 on 3 GMC models: Sierra 3500HD, Terrain, Yukon.