LEXUS SC300 1991 Service Owner's Guide

1. CONTINUITY CHECK (OPEN CIRCUIT CHECK)(1) Disconnect the connectors at both ECU and sensor sides.
(2) Measure the resistance between the applicable terminalsof the connectors.
Resistance: 1
or less
HINT:
w Measure the resistance while lightly shaking the wire
harness vertically and horizontally.
w When tester probes are inserted into a connector, insert
the probes from the back. For waterproof connectors in
which the probes cannot be inserted from the back, be
careful not to bend the terminals when inserting the
tester probes.
2. RESISTANCE CHECK (SHORT CIRCUIT CHECK) (1) Disconnect the connectors at both ends.
(2) Measure the resistance between the applicable terminalsof the connectors and body ground. Be sure to carry out
this check on the connectors on both ends.
Resistance: 1 M
or higher
HINT: Measure the resistance while lightly shaking the wire
harness vertically and horizontally.
3. VISUAL CHECK AND CONTACT PRESSURE CHECK (a) Disconnect the connectors at both ends.
(b) Check for rust or foreign material, etc. on the terminalsof the connectors.
(c) Check crimped portions for looseness or damage and check if the terminals are secured in the lock position.
HINT: The terminals should not come out when pulled lightly.
(d) Prepare a test male terminal and insert it in the female
terminal, then pull it out.
HINT: When the test terminal is pulled out more easily than
others, there may be poor contact in that section.
IN±28
±
INTRODUCTION How to Troubleshoot ECU Controlled Systems
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Actual examples of the inspection method for open circuit and short circuit ar\
e explained below.
1. OPEN CIRCUIT CHECKFor the open circuit in the wire harness in Fig. 1, perform º(a) Conti\
nuity Checkº or º(b) Voltage Checkº to
locate the section.
(a) Continuity Check
(1) Disconnect connectors (A) and (C) and measure the resistance between\
them.In the case of Fig. 2,
Between terminal 1 of connector (A) and terminal 1 of connector (C) \
±> No continuity (open)
Between terminal 2 of connector (A) and terminal 2 of connector (C) \
±> Continuity
Therefore, it is found out that there is an open circuit between terminal 1 of con\
nector (A) and terminal 1
of connector (C).
(2) Disconnect connector (B) and measure the resistance between connectors\
(A) and (B), (B) and (C).In the case of Fig. 3,
Between terminal 1 of connector (A) and terminal 1 of connector (B) \
±> Continuity
Between terminal 1 of connector (B) and terminal 1 of connector (C) \
±> No Continuity (open)
Therefore, it is found out that there is an open circuit between termina\
l 1 of connector (B) and terminal 1
of connector (C).
±
INTRODUCTION How to Troubleshoot ECU Controlled SystemsIN±29
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(b) Voltage CheckIn a circuit in which voltage is applied (to the ECU connector terminal)\
, an open circuit can be checked for
by conducting a voltage check.
(1) As shown in Fig. 4, with each connector still connected, measure the voltage between\
body ground andterminal 1 of connector (A) at the ECU 5V output terminal, terminal 1 of conne\
ctor (B), and terminal
1 of connector (C), in that order.If the results are:
5 V: Between Terminal 1 of connector (A) and Body Ground
5 V: Between Terminal 1 of connector (B) and Body Ground
0 V: Between Terminal 1 of connector (C) and Body Ground
then it is f ound out that there is an open circuit in the wire harness between termi\
nal 1 of (B) and termi-
nal 1 of (C).
2. SHORT CIRCUIT CHECK If the wire harness is ground shorted as in Fig. 5, locate the section by \
conducting a ºcontinuity check with
groundº.
IN±30±
INTRODUCTION How to Troubleshoot ECU Controlled Systems
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(a) Continuity Check with Ground
(1) Disconnect connectors (A) and (C) and measure the resistance between terminals 1 and 2 of connector(A) and body ground.
In the case of Fig. 6,
Between terminal 1 of connector (A) and body ground ±> Continuity
Between terminal 2 of connector (A) and body ground ±> No continuit\
y (open)
Therefore, it is found out that there is a short circuit between terminal 1 of con\
nector (A) and terminal 1 of
connector (C).
(2) Disconnect connector (B) and measure the resistance between terminal 1 of connec\
tor (A) and bodyground, and terminal 1 of connector (B) and body ground.
Between terminal 1 of connector (A) and body ground ±> No continuit\
y (open)
Between terminal 1 of connector (B) and body ground ±> Continuity
Therefore, it is found out that there is a short circuit between terminal 1 of con\
nector (B) and terminal 1 of
connector (C).
±
INTRODUCTION How to Troubleshoot ECU Controlled SystemsIN±31
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Check and Replace ECU
First check the ECU ground circuit. If it is faulty, repair it. If it is nor-
mal, the ECU could be faulty, so replace the ECU with a known
good one and check if the symptoms appear.
(1) Measure the resistance between the ECU ground terminal and the body ground.
Resistance: 1
or less
(2) Disconnect the ECU connector, check the ground terminals on the ECU side and the wire harness side for bend and
check the contact pressure.
IN±32
±
INTRODUCTION How to Troubleshoot ECU Controlled Systems
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VEHICLE LIFT AND SUPPORT
LOCATIONS
±
INTRODUCTION Vehicle Lift and Support LocationsIN±33
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SERVICE SPECIFICATIONS
SERVICE DATA
Idle speedMagnetic clutch no engagedApprox. 700 rpm
Magnetic clutch engaged Approx. 700 rpm
Magnetic clutch clearance0.5 + 0.15 mm0.020 + 0.006 in.
TORQUE SPECIFICATIONS
Part tightenedN Vmkgf Vcmft Vlbf
Suction hose X Compressor2525018
Discharge hose X Compressor25250 18
Compressor X EngineBolt 49500 36
Nut 29300 22
Liquid tube X Receiver10100 7
Liquid tube X Condenser10100 7
Discharge tube X Condenser10100 7
Expansion valve X Evaporator5.455 48 in. Vlbf
Suction tube X A/C Unit10100 7
Liquid tube X A/C Unit10100 7
Equalizer tube X EPR25250 18
Pressure switch X Liquid tube101007
±
AIR CONDITIONING SYSTEM Service SpecificationsAC±141
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Lexus Supports ASE CertificationPage 1 of 4
Title:
R-12 AIR CONDITIONER SYSTEM
RETROFIT
Models:
'90±'93 ES 250/300, SC 400/300, LS 400
Technical Service
Information Bulletin
April 3, 1998
AC001±98
The following information should be used for guidance when retrofitting veh\
icle air
conditioning systems from R±12 to R134a refrigerant.
1990±1992 model year LS 400, 1990±1991 model year ES 250, 1992±1993 model
year ES 300, 1992±1993 model year SC 300, 1992±1993 model year SC 400
All parts required for retrofit are available through the normal parts s\
ystem:
IDENTIFICATIONREQUIRED PARTS & MATERIALS
MODELCOMPRESSORRETROFIT SETRECEIVERND OIL 8CHARGE
LS 40010PA2088471±16050170 cc1000 g
ES 25010PA17V88840±33020 (1)
l
88471±12040100 cc650 g
ES 300plus
90099±14044 (2)SC 30010PA1790099±14044 (2)
90099±14045 (1)88471±16050150 cc900 g
SC400
90099 14045 (1)g
NOTE:
Retrofit Set 88840±33020 includes: 88374±33010 Low pressure side service fitting adaptor (7/16±20 UNF)
88374±33020 High pressure side service fitting adaptor (3/8±20 UNF)
88723±20040 R134a ªUSE ONLYº label (ND Oil 8 for 10P, 10PA compressor)
88723±33050 Retrofit Caution Label
90099±14046 Piping O±rings for discharge hose (quantity 2)
Required for all models (not included in set): 90099±14044 Receiver O±rings (quantity 2)
08885±09107 ND±Oil 8
Also available as needed: 88374±33040 L±shaped low pressure side service fitting adaptor
88374±33050 L±shaped high pressure side service fitting adaptor
OP CODENWCDESCRIPTIONTIMEOPNT1T2
Not Applicable to Warranty
Affected Vehicles page 1 . . . . . . . . . .
Service Precautions page 3 . . . . . . . .
Retrofit Kit Parts page 1 . . . . . . . . . . .
Required Parts page 2 . . . . . . . . . . . . . Required Tools & Materials page 2
. . .
Retrofitting Overview page 2 . . . . . . . . .
Repair Procedures page 3 . . . . . . . . . . .
Warranty Information page 1 . . . . . . . . .
HEATING & AIR CONDITIONING
Introduction
Affected
Vehicles
Parts
Information
Warranty
Information
Table of
Contents
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R±12 AIR CONDITIONER SYSTEM RETROFIT ± AC001±98 April 3, 1998
Page 2 of 4
A. Required Equipment:
1. R±12 recovery/recycling/recharging equipment
2. R134a recovery/recycling/recharging equipment
3. Measuring cylinder (for compressor oil)
4. Valve core remover for service valves
5. Air conditioner service tool set
6. Torque Wrench Set, P/N 00002±50284±01, includes the following*: 14 mm 00002±51410±01
17 mm 00002±51710±01
22 mm 00002±52216±01
27 mm 00002±52724±01
B. Required Parts & Materials: **
1. R134a Refrigerant
2. Service Fitting Adaptors
3. Caution Labels
4. ND±OIL 8 compressor oil (PAG type oil)
5. Receiver
6. O±Rings for compressor, line & hose connections ***
7. Loctite 262 or equivalent
* required size dependent upon model.
** see parts information section of this bulletin on page 1.
*** it is not necessary to replace any O±rings on ES 300, SC 300 and SC 400 models\
.
A. Refrigerant and Oil Charges
Oil and refrigerant charge amounts are different after the R±12 system has been
retrofitted to R134a. Refrigerant charge amounts are less, while oil ch\
arge
amounts are greater, compared to R±12 system requirements. Refer to the
ND OIL
8
and CHARGE columns in ªParts Informationº table on page 1 for proper amounts\
.
B. System Performance A slight decrease in system performance may be noticed on some vehicles \
under
certain operating conditions.
C. Refrigerant Pressures
R134a high side pressures are greater than that of R±12 above ambient\
temperatures of 68 °F.
D. Flushing Requirements There is no need to remove or flush R±12 mineral oil from the system.\
Simply
charge the system with the specified amount of ND±Oil 8 to provide pr\
oper
lubrication.
E. Use of Sight Glass Mineral based R±12 oil remains and circulates in the A/C system and d\
oes not
dissolve in R134a refrigerant. This results in a cloudy appearance at th\
e sight
glass making it impossible to judge the refrigerant charge amount by us\
ing the
sight glass method. To prevent misdiagnosis on retrofit vehicles, apply black
paint to the sight glass on block±joint (FF) type Receivers. Union\
±nut joint (BAG)
type retrofit Receivers are manufactured without a sight glass.
Required
Tools &
Materials
Retrofitting Overview
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R±12 AIR CONDITIONER SYSTEM RETROFIT ± AC001±98 April 3, 1998
Page 3 of 4
A. Refrigerant handling
1. Do not handle refrigerant in an enclosed area or near an open flame.
2. Always wear eye protection.
3. Avoid getting liquid refrigerant in your eyes or on your skin.
4. Never heat a container with an open flame.
5. Keep containers below 104 °F.
6. When heating a refrigerant can with water, keep the valve above water.
7. Never reuse empty service cans.
B. Replacing parts 1. Plug off any open connections to prevent the entry of moisture and dust.
2. Do not remove plugs from Receiver ports until it is ready for installati\
on.
C. Tightening connecting parts
1. Apply a few drops of ND±Oil 8 compressor oil to O±ring fittings be\
fore tightening.
2. Avoid twisting refrigerant piping when installing R134a service fitting a\
dapters.
3. Tighten all fittings to specified torque.
D. Recharging with A/C ªonº
1. Never open the high side valve with the engine running.
2. Never run the A/C system when low on refrigerant as compressor damage ma\
yoccur.
3. Never charge the system with liquid refrigerant with the engine running.\
4. Be careful not to overcharge the system.
NOTE:
Oil removed during R±12 evacuation should not be used with an R134a Syst\
em.
A. Vehicle Inspection:
Ensure the integrity of the A/C system before proceeding with retrofit.
B. Recover R±12 using R±12 recovery/recycling/recharging equipment: Follow Lexus recommended procedure.
C. Install R134a service fitting adapters: 1. Remove valve cores from R±12 service fittings and discard.
2. Clean external threads of the R±12 service fittings.
3. Apply adhesive to threads (Loctite 262 or equivalent), screw on R134a \
adapterfittings, and tighten to 13 ft±lb.
NOTE:
Vehicles with more than 2 service fittings will require the installation \
of additional
adaptors. All service fittings must have R134a adaptors installed.
D. Replace piping and hose O±rings:
1. Disconnect discharge hose from compressor.
2. Remove and discard old O±rings.
3. Lubricate with ND±Oil 8 and install new O±rings.
4. Disconnect discharge hose from condenser.
5. Lubricate and install retrofit O±rings with ND±Oil 8.
6. Reconnect hoses and torque to specification. (Specifications can be fou\
nd in applicable manuals/guides.)
Service
Precautions
Repair
Procedure
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