B14AA

HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM: B14AA: Glass Humidity Sensor Circuit
B14AA - Glass Humidity Sensor Circuit

DESCRIPTION

The air conditioning amplifier assembly detects the windshield glass humidity from this circuit. The air conditioning amplifier assembly applies voltage to the air conditioning thermistor assembly (glass humidity sensor). As the humidity rises, the voltage output of the sensor increases. The air conditioning amplifier assembly detects the voltage change as the humidity changes.





HINT
The whole air conditioning thermistor assembly should be replaced if the glass humidity sensor is malfunctioning.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Air Conditioner / Data List.

(e) Check the value(s) by referring to the table below.

Air Conditioner





OK:

The display is as specified in the Normal Condition column.

NG -- INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

2. INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Disconnect the T11 air conditioning thermistor assembly (glass humidity sensor) connector.





(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:





Text in Illustration





NG -- CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - GLASS HUMIDITY SENSOR)
OK -- Continue to next step.

3. INSPECT AIR CONDITIONING THERMISTOR ASSEMBLY (GLASS HUMIDITY SENSOR)

(a) Remove the air conditioning thermistor assembly (glass humidity sensor) with the connector still connected.





(b) Turn the power switch on (IG).

(c) Measure the voltage according to the value(s) in the table below.

Standard Voltage:





NOTICE:
* Do not touch the sensor as body heat will affect the inspection results. When performing the inspection, hold the sensor by its connector.
* Allow the sensor to acclimate to the ambient temperature and humidity before performing the inspection.
* The specified voltages in the table above are based on inspections performed when the ambient temperature is 25°C (77°F).

HINT
As the humidity increases, the voltage increases (see the graph).

Text in Illustration





NG -- REPLACE AIR CONDITIONING THERMISTOR ASSEMBLY Removal
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - GLASS HUMIDITY SENSOR)

(a) Disconnect the T11 air conditioning thermistor assembly (glass humidity sensor) connector.

(b) Disconnect the H85 and H86 air conditioning amplifier assembly connectors.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

5. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - GLASS HUMIDITY SENSOR)

(a) Disconnect the T11 air conditioning thermistor assembly (glass humidity sensor) connector.

(b) Disconnect the H85 air conditioning amplifier assembly connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal