Functional Test - Heater - Without A/C

Control Assembly Operational Chart:

Before beginning the functional test of the heater system, the vehicle should be idling with the coolant hot and the thermostat open. Coolant temperature should be 90°C (194°F). Even if a problem is found during any intermediate step of the functional test, the test should be completed before repair is started.

1. Set the mode knob to "VENT," temperature knob to full "COLD" (Blue) position.
^ Air at nearly the same temperature as the outside air should come from the instrument panel outlets.
^ Air should not come from the floor outlets, the defroster nozzles or the side window defogger outlets.

2. Move the mode knob to the "HTR" position, temperature knob to full "HOT" (Red) position.
^ Most of the air should come from the floor outlets with the remainder coming out of the defroster nozzles and defogger outlets and should be hot.
^ Air should not come from the instrument panel outlets in the "HTR" position.

3. Move the mode knob from the "HTR" position to the "DEFROST" position.
^ Most of the air should be discharged from the defroster nozzles and defogger outlets.
^ A small amount of air should also be discharged from the floor outlets.

4. Move the temperature knob back to the full "BLUE" position, and make sure the air temperature drops back to nearly the temperature of the outside air once again.

5. Slowly turn the blower switch toward "LO," stopping briefly at each intermediate blower speed position to notice the force of the airflow and the sound of the blower.
^ The airflow and the blower noise should reduce noticeably at each intermediate step.