Functional Test - HVAC System - Automatic

The following is a list of quick checks used to determine if the system is functioning properly. Before Initiating the quick check procedures, cycle the ignition switch ON, then OFF; and then ON again. The heater A/C temperature and mode LED's should light and repeat at the same positions as the ignition is cycled. With the ignition on, without interruption for a minimum of three minutes to allow for the blower delay to time out, test the HEAT functions. A check of the following mode sequences indicates if any mode selections are not functioning properly. The compressor will not operate at ambient temperatures below 3°C (38°F).

Inspect
^ Set temperature to 60° setting. Cold air should flow from the instrument panel outlets, blower should run at high speed, and noise level should change when in recirculation. While in the 60° Auto setting, hold a small piece of paper against the inside air temperature sensor holes. If the sensor hose is aspirating correctly, the paper will remain against the sensor holes. If not, it will fall to the floor.
^ Set temperature to 90° setting. Warm air should flow from the heater outlet and the blower should run at high speed.
^ Set temperature to 90° and select Defrost setting. Warm air should flow from the defroster outlets, and blower should run at high speed.
^ Set temperature to 75° and select Bi-Level setting. Air should flow from the instrument panel arid heater outlets and blower speed should slow down. If blower speed remains at high speed, there may be a sensor problem.
- The vehicle must be in a garage and under room temperature conditions.
- If the vehicle is hot or cold, the system will run at high blower speed at 75° and Bi-Level.