Answer :
Final answer:
Technician B is correct as airflow defaulting to defrost is for visibility, and issues with air not flowing through other vents indicate a vacuum problem.
Explanation:
Technician B is correct. The default setting for airflow in vehicles is often set to defrost because clear visibility through the windshield is crucial for safe driving. Additionally, if air fails to flow through any vents except the defrost vents, it is likely due to a vacuum problem in the system.
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