LEXUS SC400 1991 Service Repair Manual

SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 5 of 12
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 bulleti\
n, according to
the instructions in the applicable repair manual.
MODELMODEL YEARCOMMENTSPART NUMBERGRAPH
ES 3001992 ± 200188625±330702
ES 300/3302002 ± 200388625±171302ES 300/330200388625±331703
GS 3001993 ± 199788625±3A0202
GS 300/400/4301998 ± 200288625±3A1202
GX 4702003 2005Thermistor No. 188625±350503GX 4702003 ± 2005Thermistor No. 288625±162102
IS 3002000 ± 200188625±480102
1990 ± 199288625±320402
LS 4001993 ± 199488625±501002
1995 ± 200088625±501402
LS 4302001 ± 200588625±501602
LX 4501996 ± 199788625±600602
1998 ± 2000Thermistor No. 288625±601402
LX 4701998 ± 2002Thermistor No. 188625±601302
2003 ± 200588625±470112
RX 3001998 ± 200388625±480102
2004CBU88625±480501
RX 3302004 2005CBU88625 4806032004 ± 2005NAP88625±480603
SC 300/4001991 ± 200088625±320402
Inspection
Procedure
(Continued)
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 6 of 12
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:
TEMPERATURE 5F ( 5C)SPECIFICATION k W
14 (±10)7.30 to 9.10
23 (±5)5.65 to 6.95
32 (0)4.40 to 5.35
41 (5)3.40 to 4.15
50 (10)2.70 to 3.25
59 (15)2.14 to 2.58
68 (20)1.71 to 2.05
77 (25)1.38 to 1.64
86 (30)1.11 to 1.32
Graph 2:
TEMPERATURE 5F ( 5C)SPECIFICATION k W
14 (±10)7.40 to 9.20
23 (±5)5.65 to 7.00
32 (0)4.35 to 5.40
41 (5)3.40 to 4.20
50 (10)2.68 to 3.30
59 (15)2.10 to 2.60
68 (20)1.66 to 2.10
77 (25)1.32 to 1.66
86 (30)1.05 to 1.35
Inspection
Procedure
(Continued)
Resistance
k W
12.0
3.0
2.0
0.0 32
(0) 68
(20) 104
(40)
Temperature 5F ( 5C)
Max
Min
1.0 4.0 8.0
7.0
5.0 6.0 9.0
10.0 11.0
±4
(±20)
32
(0) 68
(20) 104
(40)
±4
(±20)
Resistance
k W
3.0
2.0
0.0 Temperature 5F ( 5C)
Max
Min
1.0 4.0 8.0
7.0
5.0 6.0 9.0
10.0
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 7 of 12
Graph 3:
TEMPERATURE 5F ( 5C)SPECIFICATION k W
14 (±10)8.00 to 10.00
23 (±5)6.15 to 7.65
32 (0)4.75 to 5.85
41 (5)3.70 to 4.55
50 (10)2.91 to 3.55
59 (15)2.32 to 2.80
68 (20)1.85 to 2.22
77 (25)1.48 to 1.77
86 (30)1.20 to 1.43
Inspection
Procedure
(Continued)
32
(0) 68
(20) 104
(40)
±4
(±20)
Temperature 5F ( 5C)
Resistance
k W
12.0
3.0
2.0
0.0 Max
Min
1.0 4.0 8.0
7.0
5.0 6.0 9.0
10.0 11.0
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 8 of 12
5. Inspect Solar Sensor.
Four types of solar sensors are used on Lexus 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 below\
according to
vehicle specifications and perform the inspection.
EQUIPPED WITH AUTOMATICLIGHT CONTROL SYSTEMA/C SYSTEM WITH RIGHT/LEFT
INDEPENDENT TEMPERATURE CONTROLINSPECTION
PROCEDURE
NoNoA
NoYesB
YesYesC
YesNoD
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:
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:
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 incand\
escent light for
an inspection light.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Infinite ohms
When the sensor is exposed to lightLess than infinite resistance
InspectionProcedure
(Continued)
Lock
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 9 of 12
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 incand\
escent light for
an inspection light.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Infinite ohms
When the sensor is exposed to lightLess than infinite resistance
InspectionProcedure
(Continued)
Lock
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 10 of 12
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 incandes\
cent light
for an inspection light.
Do not disconnect the solar sensor connector.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Below 0.8 V
When the sensor is exposed to light4.3 +/± 0.3 V
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 incand\
escent light
for an inspection light.
Do not disconnect the solar sensor connector.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Below 0.8 V
When the sensor is exposed to light4.3 +/± 0.3 V
InspectionProcedure
(Continued)
CLTE
TSR
TSL
CLTE
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 11 of 12
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 incandes\
cent light
for an inspection light.
Do not disconnect the solar sensor connector.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Below 0.8 V
When the sensor is exposed to light4.3 +/± 0.3 V
InspectionProcedure
(Continued)
TSD
CLTE
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 12 of 12
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 5F (25 5C).
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
ªRoom Temperature Sensor Inspection
Procedureº 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 5F
(25 5C). According to the result,
determine whether the sensor is
normal or not.
HUMIDITY (% RH)OUTPUT VOLTAGE AT 77 5F (25 5C)
100.70 to 1.08 V
200.72 to 1.57 V
301.13 to 1.95 V
401.61 to 2.24 V
501.99 to 2.46 V
602.26 to 2.66 V
702.48 to 2.85 V
802.68 to 3.04 V
902.87 to 3.05 V
Inspection
Procedure
(Continued)
VOGND
Resistance
k W
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00
32
(0) 68
(20) 104
(40) 140
(60)
Temperature 5F ( 5C)
Max
Min
176
(80) 212
(100)
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DATE:NOVEMBER 29, 1996
TitleALTERNATE REFRIGERANTS AND A/C RETROFITPage 1 of 2
Effective January 1, 1996, the E.P.A. has officially banned the manufacture of Refrigerant 12 (Freon).
As a result, surplus supplies of R±12 will begin to dwindle over the ne\
xt several years until, eventually,
R±12 will no longer be available.
This uncertainty about the availability of R±12 has caused significant concerns for Lexus dealers when
servicing HVAC systems not using R±134a refrigerant. Similarly, the reduced availability of R±12 has
prompted demands for R±134a retrofit kits and/or alternate refrigerants. Thi\
s TSB will clarify Lexus's
current recommendations for servicing and retrofitting HVAC systems on Lexus vehicles using R±12
refrigerant.
ALTERNATE REFRIGERANTS:
Previously, the E.P.A. has endorsed other alternative refrigerants. These endorsements, combin\
ed with
the uncertain future availability of R±12, have lead to a limited accept\
ance of using alternative refrigerants
when servicing or retrofitting R±12 HVAC systems. Use of these refrigerants can lead to several service
related problems, including:
Poor system performance and leak detection capabilities.
Contamination of R±12 and R±134a during refrigerant recovery and r\
ecycling.
Recently the E.P.A. released a statement clarifying that approval of alternative refrige\
rants relates only
to the toxicology, flammability, ozone depletion and global warming characteristics. The approval does
not imply acceptability of alternative refrigerants use with respect to serviceability or performance.
TOYOTA MOTOR SALES, U.S.A. ENDORSES THE USE OF R±134a AS THE ONLY ACCEPTABLE ALTERNATIVE REFRIGERANT FOR VEHICLES USING R±12.
R±12 AVAILABILITY:
It is estimated that existing R±12 supplies will meet market demand i\
n 1996. Beyond that, Lexus will
supply R±12 to it's dealers from a strategic reserve. These strategic reserves are alloca\
ted specifically
for distribution to Lexus dealers for repair of their customers' R±12 H\
VAC systems. TMS projects these
reserves may meet dealer demand through early 1998. After that, we believe R±12 will no longer be re\
adi-
ly available and dealers will begin to retrofit customer vehicles with R\
±134a.
REF: HEATING & AIR CONDITIONING
NO:AC007±96
MODEL:ALL MODELS
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ALTERNATE REFRIGERANTS AND A/C RETROFITPage 2 of 2
RETROFIT ISSUES:
Lexus has completed development of retrofit parts for all later model Le\
xus vehicles using R±12 refrigerant.
These parts will be produced in harmony with market demand, based on R±12 \
availability.
The parts necessary for a typical retrofit will generally include:Receiver Dryer
O±Rings
Fittings
Labels
Oil
A TSIB outlining retrofit procedures will be released when the retrofit \
kits become available.
For additional information, contact the Environmental Assistance Network\
Hotline at 1±800±542±3914.
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