Driver Controls and Instruments 4. Move the air selection switch to the windshield (de- frost) position, turn the air source lever to the fresh air position, and if so equipped, move the air condi- tioning on/off lever to the on position as shown in Fig. 3.35 . In this position, warm, dry air is directed to the windshield. OFF ON IMPORTANT: If equipped with an air source lever, do not operate the heater and air conditioning sys- tem with the air source lever in the recirculation mode for more than 20 minutes. This will prevent the buildup of fumes or odors inside of the cab (for example, from smoking). 10/28/94 f830369a Fig. 3.33, Dash-Face Outlet for more than 20 minutes.
This will prevent the buildup of fumes or odors inside of the cab (for example, from smoking). NOTE: At the defrost position, airflow is directed to the windshield outlets, the extreme left and right dash-face outlets, and the door window outlets. Defogging and Defrosting 1. Turn the temperature control switch all the way clockwise for warm air, turn the fan switch to off and, if so equipped, move the air conditioning on/off lever to off before starting the engine. Heating 1. With the engine at operating temperature, move the temperature control switch all the way clockwise for heat. 2. Remove any ice or snow from the outside of the windshield, door windows, and fresh air inlet grille. 3.
With the engine at operating temperature, turn the fan switch to the highest speed. Leave it in this po- sition for 30 seconds. This will clear the system of moist air. 2. Turn the fan switch to the highest speed. 3. Move the air selection switch to the desired setting and move the air source lever to the fresh air posi- tion as shown in Fig. 3.36 . 3.46