Vent Valve

When selecting the LOWER, DEFOG or FRONT DEFROST modes, the heater-A/C control energizes the A/C solenoid. This action causes the vent valves to move to position A, and airflow is not sent through the I/P outlets.
When selecting the UPPER mode, the heater-A/C control energizes the bi-level solenoid. This action causes the vent valves to move to position C, and airflow is sent through the I/P outlets. When selecting the BI-LEVEL mode, the heater-A/C control de-energizes both the bi-level and A/C solenoids. This action causes the vent valve to move to position B (neutral position), and airflow is sent through both the I/P and heater outlets.