Lexus SC300 / Lexus SC400. Service manual — part 947

Lexus Supports ASE Certification

Page 1 of 12

Title:

SENSOR INSPECTION FOR AIR

CONDITIONING SYSTEM

Models:

’90 – Current All Models

Technical Service

Information Bulletin

December 16, 2004

A

C

005-04

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.

S

Room Temperature Sensor

S

Ambient Temperature Sensor

S

Air Duct Sensor

S

Evaporator Temperature Sensor

S

Solar Sensor

S

Room Humidity Sensor

S

All 1990 – Current model year Lexus vehicles.

OP CODE

DESCRIPTION

TIME

OFP

T1

T2

N/A

Not Applicable to Warranty

–

–

–

–

HEA

TING & AIR CONDITIONING

Introduction

Applicable

Vehicles

Warranty

Information

SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM – AC005-04

December 16, 2004

Page 2 of 12

1. Inspect Room Temperature Sensor.

A. Measure the sensor resistance.

Resistance Value at 77

°

F

(25

°

C)

1700 +/– 85

Ω

NOTE:

S

Even slightly touching the sensor
may change the resistance value.
Be sure to hold the connector of
the sensor.

S

When measuring, the sensor
temperature must be the same as
the ambient temperature.

HINT:

As the temperature increases, the
resistance decreases.

TEMPERATURE

°

F (

°

C)

SPECIFICATION k

Ω

50 (10)

3.00 to 3.73

59 (15)

2.45 to 2.88

68 (20)

1.95 to 2.30

77 (25)

1.60 to 1.80

86 (30)

1.28 to 1.47

95 (35)

1.00 to 1.22

104 (40)

0.80 to 1.00

113 (45)

0.65 to 0.85

122 (50)

0.50 to 0.70

131 (55)

0.44 to 0.60

140 (60)

0.36 to 0.50

Inspection

Procedure

Resistance
k

Ω

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

32

(0)

68

(20)

104

(40)

140

(60)

Temperature

°

F (

°

C)

Max

Min

SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM – AC005-04

December 16, 2004

Page 3 of 12

2. Inspect Ambient

Temperature Sensor.

A. Measure the sensor resistance

according to the selected graph
(specification).

Resistance Value at 77

°

F

(25

°

C)

1700 +/– 85

Ω

NOTE:

S

Even slightly touching the sensor
may change the resistance value.
Be sure to hold the connector of
the sensor.

S

When measuring, the sensor
temperature must be the same as
the ambient temperature.

HINT:

As the temperature increases, the
resistance decreases.

TEMPERATURE

°

F (

°

C)

SPECIFICATION k

Ω

50 (10)

3.00 to 3.73

59 (15)

2.45 to 2.88

68 (20)

1.95 to 2.30

77 (25)

1.60 to 1.80

86 (30)

1.28 to 1.47

95 (35)

1.00 to 1.22

104 (40)

0.80 to 1.00

113 (45)

0.65 to 0.85

122 (50)

0.50 to 0.70

131 (55)

0.44 to 0.60

140 (60)

0.36 to 0.50

Inspection

Procedure

(Continued)

Resistance
k

Ω

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

32

(0)

68

(20)

104

(40)

140

(60)

Temperature

°

F (

°

C)

Max

Min

SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM – AC005-04

December 16, 2004

Page 4 of 12

3. Inspect Air Duct Sensor.

A. Measure the sensor resistance

according to the table and
graph (specification).

NOTE:

S

Even slightly touching the sensor
may change the resistance value.
Be sure to hold the connector of
the sensor.

S

When measuring, the sensor
temperature must be the same as
the ambient temperature.

HINT:

As the temperature increases, the
resistance decreases.

TEMPERATURE

°

F (

°

C)

SPECIFICATION k

Ω

50 (10)

9.48 to 10.49

59 (15)

7.50 to 8.28

68 (20)

5.95 to 6.57

77 (25)

4.77 to 5.25

86 (30)

3.85 to 4.21

95 (35)

3.12 to 3.40

104 (40)

2.53 to 2.79

113 (45)

2.06 to 2.30

122 (50)

1.69 to 1.91

131 (55)

1.39 to 1.59

140 (60)

1.15 to 1.33

Inspection

Procedure

(Continued)

Resistance
k

Ω

15.0

10.0

5.0

0.0

32

(0)

68

(20)

104

(40)

140

(60)

Temperature

°

F (

°

C)

Max

Min

176

(80)