1991 LEXUS SC400 lock

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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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 4 of 4
E. Replace Receiver
1. Remove original R±12 Receiverand discard.
2. Measure oil and pour 1/2 of specified amount of oil into the
ªOUTº side of new Receiver (see
table on page 1 for amount).
3. Black out the sight glass on block ± joint ± type Receiver with black
paint.
4. Lubricate and install the O±rings on the Receiver connections.
5. Install Receiver.
F. Using R134a Recovery equipment,
evacuate, charge, and leak test the
system (Use equipment
manufacturer 's recommended
procedure).
1. Evacuate for 45 minutes.
2. Vacuum check.
3. If vacuum check is OK, add remaining 1/2 compressor oil using
the recovery equipment.
Using recovery / recycling /
recharging equipment charge
the system with the remaining
½ of the specified amount of oil
from step E2.
4. Charge system with specified amount of R134a. (reference table
on page 1).
5. Perform a gas leak check.
G. Confirm cooling performance of Air Conditioning system.
H. Install retrofit labels:
1. Choose R134a ªUSE ONLYº label
for proper oil type ( ND±OIL 8).
2. Using a ball point pen, enter the proper retrofit refrigerant and oil
charges on the caution label.
3. Cross out unused type of compressor oil on caution label.
4. Affix labels in a prominent location such as radiator support, underside
of hood, or suspension tower area.
5. Remove any R±12 labels.Repair
Procedure
(continued)FF Type
Black out
Replace O±Rings
Retrofit Receiver
BAG type
Replace O±Ring
Retrofit Receiver
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wTighten the O±ring fittings or the bolted type fittings to
the specified torque.
Precautions When Charging Refrigerant
1. DO NOT OPERATE COMPRESSOR WITHOUT ENOUGH
REFRIGERANT IN REFRIGERANT CYCLE
If there is not enough refrigerant in the refrigerant cycle, oil
lubrication will be insufficient and compressor burnout may
occur, so take care to avoid this.
2. DO NOT OPEN HIGH PRESSURE VALVE OF MANIFOLD GAUGE WITH COMPRESSOR OPERATING
If the high pressure valve is opened, refrigerant flows in the
reverse direction and could cause the charging cylinder to
rupture, so open and close the low pressure valve only.
3. BE CAREFUL NOT TO OVERCHARGE WITH REFRIGERANT IN SYSTEM
If refrigerant is overcharged, it causes trouble such as insuffi-
cient cooling, poor fuel economy, engine overheating etc.
Electrical Parts
Before removing and inspecting the electrical parts, set the
ignition switch to the LOCK position and disconnect the neg-
ative (±) terminal cable from the battery.
CAUTION: Work must not be started until after at least 20
seconds or longer from the time the negative (±) terminal
cable is disconnected.
SRS Airbag System
Failure to carry out service operations in the correct se-
quence could cause the airbag system to deploy, possibly
leading to a serious accident.
When removal or installation of the parts and the yellow wire
harness and connector for the airbag is necessary, refer to
the precautionary notices in the AB section before perform-
ing the operation.
±
AIR CONDITIONING SYSTEM General DescriptionAC±5
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DIAGNOSIS SYSTEM
Warning for A/C compressor lock
If compressor lock occurs during air conditioner operation, the
( A/C ) switch indicator on the air conditioner control assembly
starts blinking to warn the driver.
When this occurs, check for compressor lock (code 22) using diag-
nostic code check then proceed to inspect the circuit or the com-
ponent.
Compressor lock sensor circuit page AC±54.
LIST OF OPERATION METHODS
By operating each of the air conditioner control switches as shown in the \
diagram below, it is possible to enter
the diagnosis check mode. AC±26
±
AIR CONDITIONING SYSTEM Troubleshooting
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INDICATOR
1. Turn the ignition switch on while pressing the ari conditioner control
switch and REC swich
simultaneously.
2. Check that all the indicators light up and go off at 1 second intervals 4 times in succession.
3. Check that the buzzer sounds when the indicators light up in 2.
HINT:
wAfter the indicator check is ended, the diagnostic code
check begins automatically.
w Press the OFF switch when desiring to cancel the check
mode.
DIAGNOSTIC CODE CHECK (SENSOR
CHECK)
1. Perform an indicator check. After the indicator check is completed, the system enters the diagnostic code check
mode automatically.
2. Read the code displayed on the panel. Refer to the list of
codes on page AC±28 when reading the codes. (Codes are
output at the temperature display.)
If the slower display ped is desired, press the FRS
switch and change it to stepped operation. Each time the
FRS
switch is pressed, the display changes by 1 step.
HINT:
w If the buzzer sounds when a code is being read, it means
the trouble indicated by that code continues to occur.
w If the buzzer does not sound when a code is being read,
it means the trouble indicated by that code occurred ear-
lier (such as poor connector contacts, etc.)
CLEARING DIAGNOSTIC CODES
1. Pull out the DOME fuse in Relay Block No. 2 for 10 sec. or
longer to clear the memory of diagnostic codes.
2. After reinserting the fuse, check that the normal code is output.
±
AIR CONDITIONING SYSTEM TroubleshootingAC±27
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Trouble AreaMemory*5See page
±±±
 Room temp. Sensor
 Harness or connector between room temp. sensor and A/C control assembly\
 A/C control assemblyO
(8.5 min. or more)AC±44
 Ambient temp. sensor
 Harness or connector between ambient temp. sensor and A/C control assem\
bly
 A/C control assemblyO
(8.5 min. or more)AC±46
 Evaporator temp. sensor
 Harness or connector between evaporator temp. sensor and A/C control
assembly A/C control assemblyO
(8.5 min. or more)AC±48
 Water temp. sensor
 Harness or connector between water temp. sensor and A/C control assembl\
y
 A/C control assemblyO
(8.5 min. or more)AC±50
 Solar sensor
H b d A/C l bl
±
AC 52 Solar sensor
 Harness or connector between sensor and A/C control assembly
 A/C control assemblyOAC±52
 A/C control assemblyO
(8.5 min. or more)
 Compressor drive belt Compressor lock sensor Compressor
 Harness and connector between A/C control assembly and compressor,
 compressor lock sensor
 A/C control assembly
±AC±54
 Pressure switch
 Harness or connector between pressure switch and A/C control assembly
 Refrigerant pipe line
 A/C control assembly
±AC±56
 Air mix damper position sensor A/C control assembly
 Harness or connector between air mix damper position sensor and
A/C control assemblyO
(1 min. or more)AC±58
 Air inlet damper position sensor A/C control assembly
 Harness or connector between air inlet damper position sensor and
A/C control assemblyO
(1 min. or more)AC±62
 Air outlet damper position sensor A/C control assembly
 Harness or connector between air outlet damper position sensor and
A/C control assemblyO
(1 min. or more)AC±66
 Air mix servomotor Air mix damper position sensor
 Harness and connector between A/C control assembly and air mix position\
sensor
 Harness and connector between A/C control assembly and air mix servomot\
or.O
(15 secs. or more)AC±58
AC±60
 Air inlet servomotor Air inlet damper position sensor
 Harness and connector between A/C control assembly and air inlet positi\
on sensor.
 Harness and connector between A/C control assembly and air inlet servom\
otor.O
(15 secs. or more)AC±62
AC±64
 Air outlet servomotor Air outlet damper position sensor
 Harness and connector between A/C control assembly and air outlet posit\
ion
sensor.
 Harness and connector between A/C control assembly and air outlet servo\
motor.
 A/C control assembly
O
(15 secs. or more)AC±66
AC±68
±
AIR CONDITIONING SYSTEM TroubleshootingAC±29
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Diag. Code 22Compressor Lock Sensor Circuit
CIRCUIT DESCRIPTION
This sensor sends 4 pulses per engine revolution to the air conditioner cont\
rol assembly.
If the number ratio of the compressor speed, divided by the engine speed i\
s smaller that a predetermined
value, the air conditioner control assembly turns the compressor off. And, the indicator flashes at about
1 second intervals.
Code No.Diag. Code Detecting ConditionTrouble area
22
All conditions below are detected for 3 secs.
or more. (a) Engine rpm: 450 rpm or more
(b) Ratio between engine and compressor
rpm deviates 20% or more in comparison to
normal operation.
Compressor

Compressor drive belt.

Compressor lock sensor.

Harness and connector between compressor
and A/C control assembly.

A/C control assembly.
DIAGNOSTIC CHART
Check compressor.
Check compressor lock sensor.
Check harness and connectors between air
conditioner control assembly and compres-
sor sensor (See page IN-27).
Proceed to next circuit inspection shown on
matrix chart (See page AC-36). However,
when Diag. code 22 is displayed, check
and replace air conditioner control assem-
bly.
Adjust drive belt tension or repair
compressor.
Replace compressor lock sensor.
Repair or replace harness or
connector.
AC±54±
AIR CONDITIONING SYSTEM Troubleshooting
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