B0423 on Chevrolet: How to Diagnose & Fix
Air Temperature Control (Passenger/Right Side) Circuit Performance
2 Chevrolet models · 2 documented issues · $120-$500 repair
B0423 on Chevrolet by model: symptoms, diagnosis and fix
The plastic gears inside the HVAC air temperature and mode (defrost) actuators strip, so the door stops reaching its commanded position and the actuator motor hunts back and forth. The signature is a rapid clicking or ticking from behind the dash, usually when the temperature or mode is changed or right after startup, together with air that stays cold on one side while the other side blows hot, or airflow stuck on defrost. Owners often mistake it for a low refrigerant charge or a plugged heater core, but the temperature split between left and right vents points at the blend door.
Common Symptoms
- Rapid clicking or ticking behind the dashboard
- Cold air on one side, hot on the other
- Temperature knob has no effect
- Airflow stuck on defrost or won't change mode
- Clicking that starts on ignition on
How to Fix
Confirm by commanding the actuator through a scan tool's HVAC output test and listening for the clicking, or by pulling the actuator and checking whether its output gear teeth are stripped. Replace the affected actuator (air temperature actuator sits behind the left lower instrument panel on the HVAC case; the mode/defrost actuator is a separate unit) and then run the HVAC calibration/recalibration procedure so the module relearns the door end stops - skipping the relearn makes a good new actuator behave like a failed one.
Sources for this issue (2)
The plastic gears inside the HVAC blend-door actuator strip over time, so the actuator motor spins without moving the temperature-mix door. Owners hear a repetitive clicking or knocking behind the dash (often on start-up or when changing temperature) and get uneven output such as cold air on one side and warm on the other, or the temperature not matching the setting. This is a common, well-documented Camaro complaint on Camaro5 and general GM HVAC references, mirroring the same actuator failure across the GM lineup.
Common Symptoms
- Repetitive clicking or knocking behind the dash
- Air only hot or only cold
- Different temperature left vs right vents
- Temperature not matching the setting
- Noise worst at startup or on temp change
How to Fix
Confirm the failing actuator by the clicking location and by commanding temperature sweeps with a scan tool. A relearn/reset can occasionally recover a sticking actuator, but stripped gears require replacing the affected blend-door actuator (an inexpensive part; labor varies with how deep in the dash the actuator sits). Recalibration may be needed after replacement.
Sources for this issue (1)
B0423 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does B0423 mean on a Chevrolet?
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 Chevrolet it is documented across 2 models: Cruze, Camaro.
What are the most common causes of B0423?
The most common causes of B0423 are: 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. The specific cause varies by vehicle.
How much does it cost to fix B0423 on a Chevrolet?
Published repair estimates on Chevrolet range from $120 to $500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for B0423 on a different make?
View B0423 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.