Canada - A/C - Sensor Inspection Procedures
Bulletin
TSB2154
Issue Date
April 18, 2005
Market
Canada
Title
SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM
Component
HEATING & AIR CONDITIONING
Models
'89 - Current All Models
INTRODUCTION:
This service bulletin contains inspection procedures to more precisely confirm proper operation of the following temperature sensors of the air conditioning system. Follow the procedures in this service bulletin when inspecting these sensors. These contents will be reflected in future repair manuals.
- Room Temperature Sensor
- Ambient Temperature Sensor
- Air Duct Sensor
- Evaporator Temperature Sensor
- Solar Sensor
- Room Humidity Sensor
APPLICABLE VEHICLES:
- All 1989 - Current model year Toyota vehicles.
WARRANTY INFORMATION:
INSPECTION PROCEDURE:
1. Inspect Room Temperature Sensor.
A. Measure the sensor resistance.
NOTE:
- Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
- When measuring, the sensor temperature must be the same as the ambient temperature.
HINT:
As the temperature increases, the resistance decreases.
2. Inspect Ambient Temperature Sensor.
A. Measure sensor resistance according to the selected graph (specification).
NOTE:
- Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
- When measuring, the sensor temperature must be the same as the ambient temperature.
HINT:
As the temperature increases, the resistance decreases.
3. Inspect Air Duct Sensor.
A. Measure the sensor resistance according to the table and graph (specification).
NOTE:
- Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
- When measuring, the sensor temperature must be the same as the ambient temperature.
HINT:
As the temperature increases, the resistance decreases.
4. Inspect Evaporator Temperature Sensor.
Select the appropriate graph (specification) using the following table.
NOTE:
Please inspect the sensors for model years not indicated by this bulletin, according to the instructions in the applicable repair manual.
A. Measure the sensor resistance according to the selected graph (specification).
NOTE:
- Even slightly touching the sensor may change the resistance value.
- Be sure to hold the connector of the sensor.
- When measuring, the sensor temperature must be the same as the ambient temperature.
HINT:
As the temperature increases, the resistance decreases.
Graph 1:
Graph 2:
Graph 3:
Graph 4:
5. Inspect Solar Sensor.
Four types of solar sensors are used on Toyota vehicles depending on the vehicle specifications. The inspection procedure for each type of sensor differs from the others. Select the appropriate inspection procedure from the table according to vehicle specifications and perform the inspection.
Procedure A:
a. Disconnect the solar sensor connector.
b. Measure the resistance between terminals 1 and 2 of the solar sensor under the following conditions:
a. Cover the sensor with a cloth to avoid direct light.
b. Expose the sensor to light from a distance of 300 mm (11.81 in.) or less with an inspection light.
NOTE:
Terminal 1 of the sensor is always on the right, when the lock is facing up.
When using an analog tester, connect the positive (+) lead to terminal 2 and negative (-) lead to terminal 1 of the solar sensor.
HINT:
If the light is weak, the sensor may not react. Be sure to use an incandescent light for an inspection light.
Standard:
Procedure B:
a. Disconnect the solar sensor connector.
b. Measure the resistance between terminals 2 and 3 of the solar sensor under the following conditions:
- Cover the sensor with a cloth to avoid direct light.
- Expose the sensor to light from a distance of 300 mm (11.81 in.) or less with an inspection light.
NOTE:
When using an analog tester, connect the positive (+) lead to terminal 3 and negative (-) lead to terminal 2 of the solar sensor.
HINT:
If the light is weak, the sensor may not react. Be sure to use an incandescent light for an inspection light.
Standard:
Procedure C:
a. Turn the ignition switch ON.
b. Measure the voltage between terminals TSR (+) and CLTE (-) of the connector under the following conditions:
- Cover the sensor with a cloth to avoid direct light.
- Expose the sensor to light from a distance of 300 mm (11.81 in.) or less with an inspection light.
HINT:
- If the light is weak, the sensor may not react. Be sure to use an incandescent light for an inspection light.
- Do not disconnect the solar sensor connector.
Standard:
C. Measure the voltage between terminals TSL (+) and CLTE (-) of the connector under the following conditions:
- Cover the sensor with a cloth to avoid direct light.
- Expose the sensor to light from a distance of 300 mm (11.81 in.) or less with an inspection light.
HINT:
- If the light is weak, the sensor may not react. Be sure to use an incandescent light for an inspection light.
- Do not disconnect the solar sensor connector.
Standard:
Procedure D:
a. Turn the ignition switch on.
b. Using the tester, measure the voltage between terminals TSD (+) and CLTE (-) of the connector under the following conditions:
- Cover the sensor with a cloth to avoid direct light.
- Expose the sensor to light from a distance of 300 mm (11.81 in.) or less with an inspection light.
HINT:
- If the light is weak, the sensor may not react. Be sure to use an incandescent light for an inspection light.
- Do not disconnect the solar sensor connector.
Standard:
6. Inspect Room Humidity Sensor.
Measure the humidity and output voltage of the humidity sensor when the sensor is installed on the vehicle and the temperature at the humidity sensor position (room temperature sensor position) is 77°F (25°C). If the output voltage is within the specifications according to the graph and table below, the sensor is normal.
HINT:
For the inspection procedure of the room temperature sensor, refer to "Room Temperature Sensor Inspection Procedure" in this bulletin.
A. Turn the ignition switch to the ON position.
B. Measure the voltage between terminal VO (3) and GND (2) of the room humidity sensor.
C. Measure the humidity and voltage when the room temperature (humidity sensor position) is 77°F (25°C). According to the result, determine whether the sensor is normal or not.
NOTE:
Issue of this Technical Service Bulletin is to ensure that proper repair information is available. IT DOES NOT CONSTITUTE AN AUTHORIZATION FOR REPAIR. Normal provisions of the formal warranty policy, as applicable, will apply.