B0429 on GMC
Auxiliary Air Temperature Actuator Range/Performance
B0429 on GMC vehicles indicates auxiliary air temperature actuator range/performance. Au7o has documented this code across 1 GMC model — most commonly on Yukon. A body code used by General Motors (Chevrolet, GMC, Cadillac) for the auxiliary — typically rear — air temperature blend actuator; some references also render it as rear temperature control circuit out of range. The auxiliary HVAC actuators are 5-wire bi-directional motors with a built-in feedback potentiometer using a low reference, 5-volt reference, position signal, and two control circuits. As the actuator shaft rotates, the position signal varies between 0 and 5 volts, which the module converts to counts (1 volt equals 51 counts, so 0-255); B0429 sets when the reported position falls outside the expected range. The symptom is rear or auxiliary-zone air that will not change temperature, stays stuck hot or cold, or a clicking noise behind the trim. This is a comfort fault, not a drivability or safety issue. Typical repair costs on GMC range from $60 to $500, depending on the specific model and root cause.
Common Causes of B0429
- •Failed auxiliary/rear air temperature actuator (stripped gears or a failed feedback potentiometer are common)
- •Actuator harness open or shorted
- •Poor electrical connection at the actuator — corroded or loose connector
- •Blend door binding or broken off its pivot
- •Failed HVAC control module
- •Actuator not recalibrated after battery disconnect or replacement
B0429 on GMC by Model
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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What does B0429 mean on GMC?▼
B0429 stands for "Auxiliary Air Temperature Actuator Range/Performance." A body code used by General Motors (Chevrolet, GMC, Cadillac) for the auxiliary — typically rear — air temperature blend actuator; some references also render it as rear temperature control circuit out of range. The auxiliary HVAC actuators are 5-wire bi-directional motors with a built-in feedback potentiometer using a low reference, 5-volt reference, position signal, and two control circuits. As the actuator shaft rotates, the position signal varies between 0 and 5 volts, which the module converts to counts (1 volt equals 51 counts, so 0-255); B0429 sets when the reported position falls outside the expected range. The symptom is rear or auxiliary-zone air that will not change temperature, stays stuck hot or cold, or a clicking noise behind the trim. This is a comfort fault, not a drivability or safety issue. On GMC specifically, this code is documented across 1 model.
What causes B0429 on GMC vehicles?▼
Common causes on GMC: Failed auxiliary/rear air temperature actuator (stripped gears or a failed feedback potentiometer are common), Actuator harness open or shorted, Poor electrical connection at the actuator — corroded or loose connector, Blend door binding or broken off its pivot, Failed HVAC control module. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix B0429 on a GMC?▼
Repair costs on GMC range from $60 to $500, depending on the specific model and root cause.
Which GMC models have B0429 documented?▼
Au7o has documented B0429 on 1 GMC model: Yukon.