Automotive Service Excellence (ASE) Air Conditioner Certification Practice Exam 2026 - Free ASE Air Conditioner Practice Questions and Study Guide

The correct choice is that both a faulty check valve in the vacuum reservoir and a vacuum leak in the system could cause the air conditioning system's cold air to shift from the dash outlets to the floor upon acceleration.

In many automotive air conditioning systems, different modes of air distribution (such as from the dash to the floor) are controlled using vacuum-operated actuators. When the driver accelerates, increased engine load can affect the available vacuum. If there's a faulty check valve in the vacuum reservoir, it may not maintain adequate vacuum pressure, resulting in the HVAC control system not holding the selected air distribution mode.

Similarly, a vacuum leak in the system can reduce the pressure needed to keep the air directed to the desired outlets. If a vacuum leak occurs, the system may not be able to effectively direct the airflow, causing it to revert to a default position, which is often the floor outlets.

This interplay between vacuum pressure and control of airflow distribution is key in how air conditioning systems manage where the air is directed. Therefore, both conditions are relevant in causing the symptoms described.