Functional Test - Without A/C

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 close to 90° C (194° F). During the functional test, the operating efforts of the mode rotary knob and the temperature rotary knob should be evaluated. If a problem is found during any intermediate step of the functional test, complete the test before the repair is started.

1. Cycle the temperature rotary knob to the extreme ends of travel on the control assembly dial to ensure that the cable is properly adjusted.
2. Move the mode rotary knob to the "VENT" position.
- Air should come from the instrument panel outlets at nearly the same temperature as the outside air.
- Air should not come from the floor outlets, the defroster nozzles, or the side window defogger outlets.
3. Move the mode rotary knob to the "HEATER" position,
- Most of the air should come from the floor outlets with the remainder coming out of the defroster nozzles and defogger outlets.
- Air should not come from the instrument panel outlets in the "HEATER" position.
4. Move the mode rotary knob from the "HEATER" position to the "DEFROST" position.
- Most of the air should be discharged onto the windshield from the defroster nozzles.
- A small amount of air should also be discharged from the floor outlets.
5. Move the temperature rotary knob back to the full "COLD" position and make sure the air temperature drops back to nearly the temperature of the outside air once again.
6. Slowly turn the blower switch toward off, stopping briefly at each intermediate blower speed position to notice the force of the airflow coming from the instrument panel center outlets and the sound of the blower.
- Both the airflow and the blower noise should reduce noticeably at each intermediate step.