Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2019TAHOE LS, 4WD, GAS/ETHANOLREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 77 (HVAC SYSTEM - MANUAL)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B0223CIRCUIT/SYSTEM TESTING
2019 Chevrolet Tahoe LS, 4WD, Gas/Ethanol
Circuit/System Testing
2019 Chevrolet Tahoe LS, 4WD, Gas/EthanolSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2018 Chevrolet Sonic. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector at the M4 Air Inlet Door Actuator.
- Connect a test lamp between control circuit terminal 1 and control circuit terminal 2, ignition ON.
- Verify the test lamp turns ON for approximately 10 s when commanding the RECIRCULATE and FRESH AIR positions using the recirculate switch.
- If the test lamp does not turn ON and OFF during either of the commands
- Ignition OFF, remove the test lamp and disconnect the X3 harness connector at the K33 HVAC Control Module, ignition ON.
- Test for less than 1 V between each control circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Test for infinite resistance between each control circuit and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in each control circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K33 HVAC Control Module.
- Go to next step: If the test lamp turns ON and OFF during each of the commands
- Test or replace the M4 Air Inlet Door Actuator.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.