Ambient Temperature Sensor / Switch HVAC: Testing and Inspection

COMPONENT DESCRIPTION
The ambient sensor is attached in front of the driver's side condenser. It detects ambient temperature and converts it into a resistance value which is then input into the auto amplifier.

AMBIENT TEMPERATURE INPUT PROCESS
The automatic amplifier includes a "processing circuit" for the ambient sensor input. However, when the temperature detected by the ambient sensor increases quickly, the processing circuit retards the auto amp. function. It only allows the auto amp. to recognize an ambient temperature increase of 0.33° C (0.6° F) per 100 seconds. As an example, consider stopping for a cup of coffee after high speed driving. Although the actual ambient temperature has not changed, the temperature detected by the ambient sensor will increase. This is because the heat from the engine compartment can radiate to the front grille area, location of the ambient sensor.

Step 1:

Step 2:

Step 3:

Step 4:

DIAGNOSTIC PROCEDURE
SYMPTOM: Ambient sensor circuit is open or shorted. (21 or -21 is indicated on the display as a result of conducting Self-diagnosis STEP 2.)

COMPONENT INSPECTION







Ambient Sensor
After disconnecting ambient sensor harness connector, measure resistance between terminals 2 and 1 at sensor harness side, using the table.
If NG, replace ambient sensor.