Temperature Control Lever
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 1999 Isuzu Rodeo, 1999 Isuzu Amigo, 1999 Honda Passport, 1998 Isuzu Rodeo, and 1998 Isuzu Amigo. However, it is still accessible from the selected car via links, so may be relevant.
Lever controls blend-air door position. Depending on lever position, airflow is directed through heater core (hot setting), around heater core (cold setting) or through and around heater core, resulting in modulated temperatures between full hot and full cold.