Functional Test - Heater - Without A/C

The following operational test sequence will aid in determining whether the heater system is working properly. Coolant temperature should he close to 90°C (194°F).

PREPARATION

Engine should he started and allowed to idle for about 20 minutes or until thermostat is open.

TEST

1. Set mode control knob to bi-level, temperature control knob all the way to the left and blower switch to "HIGH.

^ Air at nearly the same temperature as outside air should come from all outlets.

2. Set mode control knob to vent.

^ Air at nearly the same temperature as outside air should come from instrument panel outlets.
^ Air should not come from floor outlets, defroster nozzle or side window defogger outlets.

3. Move mode control knob to the heater position.

^ Most of the air should come from floor outlets with remainder coming out of defroster nozzle and defogger outlets.
^ Air should not come from instrument panel outlets in heater position.
^ All air from heater system should be at nearly the same temperature as outside air.

4. Move the mode control knob from heater position to the blend position. Air should come equally from the defroster nozzle and the heater outlet with some air coming from the side window defogger.

5. Move mode control knob from blend position to defrost position.

^ Most of the air should he discharged onto the windshield from the defroster nozzle.
^ A small amount of air should also be discharged from floor outlets.

6. Move mode control knob back to bi-level position and rotate temperature control knob clockwise to full hot.

^ Air should come from instrument panel outlets, and its temperature should climb rapidly to approximately 55°C (131°F) or higher, depending upon outside air temperature. For a more precise heater output temperature check, refer to "Heater Output Temperature Check." Heater Output Temperature Check
^ Defroster nozzle airflow should diminish and airflow from floor outlets may increase slightly.

7. Rotate temperature control knob counterclockwise to full cold and check to he sure air temperature drops back to nearly the temperature of the outside air once again.

8. Slowly turn blower motor speed control knob toward "OFF," stopping briefly at each intermediate position to feel the reduction of airflow.

^ Both airflow and blower noise should reduce noticeably at each intermediate step.