check LEXUS SC300 1991 Service Owner's Manual

(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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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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EVACUATING AIR IN
REFRIGERATION SYSTEM AND
CHARGING WITH REFRIGERANT
HINT: Before charging the system with refrigerant, be sure
carry out a complete evacuation of the system.
1. INSTALL MANIFOLD GAUGE SET TO SERVICE VALVES See page AC±15
2. EVACUATE AIR IN REFRIGERATION SYSTEM (a) Connect the center hose of the manifold gauge set to the vacuum pump.
(b) Open both the high and low hand valves and run the vacuum pump.
HINT: If opening the low pressure hand valve pulls the high
pressure gauge into the vacuum range, there is no blokage
in the system.
(c) After ten minutes or more, check that the low pressure gauge indicates 99.99 kPa (750 mmHg, 29.53 in.Hg) or
more of vacuum.
HINT: If the reading is not 99.99 kPa (750 mmHg, 29.53
in.Hg) or more of vacuum, close both the high and low hand
valves of the manifold gauge set and stop vaccum pump.
Then, check the system for leaks and repair as necessary.
(d) Close both the high and low hand valves and stop the
vacuum pump.
(e) Leave the system in this condition for five minutes or longer and check that there is no change in the gauge
indicator.
3. INSTALL CHARGING CYLINDER NOTICE: When handling the charging cylinder, always
follow the directions given in the instruction manual.
(a) Charge the proper amount of refrigerant in charging cylinder.
(b) Connect the center hose to charging cylinder. NOTICE: Do not open both high and low hand valves of
manifold guage set.
(c) Press on the schrader valve on the side of manifold gauge and expel the air inside of the center hose.
±
AIR CONDITIONING SYSTEM Evacuation Air in Refrigeration
System and Charging with RefrigerantAC±17
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4. INSPECT REFRIGERATION SYSTEM FOR LEAKSHINT: After evacuating the air in system, check the system for
leakage.
(a) Open the high pressure hand valve to charge the system with refrigerant.
(b) When the low pressure g auge indicates 98 kPa (1
kgf/cm, 14 psi), close the high pressure hand valve.
(c) Using a gas leak tester, check the system for leakage. If leak is found, repair the faulty component or connection.
5. CHARGE EMPTY REFRIGERATION SYSTEM WITH REFRIGERANT (LIQUID)
HINT: This step is used to charge an empty system through
the high pressure side with refrigerant in a liquid state.
NOTICE:
wNever run the engine when charging the system
through the high pressure side with refrigerant in a
liquid stae.
w Do not open the low pressure hand valve when the
system is being charged with liquid refrigerant.
(a) Open the high pressure hand valve fully.
(b) Charge the system with specified amount of refrigerant, then close the high pressure hand valve.
HINT:
w A fully charged system is indicated by the sight glass
being free of any bubbles.
w If the low pressure gauge does not show a reading, the
system is clogged and must be repaired.
AC±18
±
AIR CONDITIONING SYSTEM Evacuation Air in Refrigeration
System and Charging with Refrigerant
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HOW TO PROCEED WITH TROUBLESHOOTING
Perform troubleshooting in accordance with the procedure on the following page.\
[1] CUSTOMER PROBLEM ANALYSIS Using the customer problem analysis check sheet for reference, ask the c\
ustomer in as much detail as
possible about the problem. A subjective complaint such as ºpoor air conditio\
ner efficiencyº is also consid-
ered in the air conditioner complaints.
Therefore, in ºCustomer Problem Analysisº and ºProblem Symptom Confirmationº\
, check carefully to deter-
mine whether the level of performance is the actual (normal) level or whet\
her it is abnormal. Then perform
troubleshoot accordingly.
[2] CHECK AND CLEAR THE DIAGNOSTIC CODES (PRECHECK) First check the diagnostic codes to see if there are any malfunction cod\
es stored in memory. If there are
malfunction codes, make a note of them, then clear them and proceed to [3] problem \
Symptom Confirma-
tionº.
[3] PROBLEM SYMPTOM CONFIRMATION, [4] SYMPTOM SIMULATION Confirm the problem symptoms. If the problem does not reappear, be sure to simulate the problem by main-
ly checking the circuits indicated by the diagnostic code in step [2], u\
sing ºProblem Simulation Methodº.
[5] DIAGNOSTIC CODE CHECK
Check the diagnostic codes. Check for problems with the sensors or the w\
ire harness.
[6] DIAGNOSTIC CODE CHART If a malfunction code is confirmed in the diagnostic code check, proceed t\
o the check procedure indicated
by the matrix chart for each diagnostic code.
[7] MATRIX CHART OF PROBLEM SYMPTOMS
If the normal code is confirmed in the diagnostic code check, perform in\
spection in accordance with the
inspection order in the matrix chart of problem symptoms.
[8] CIRCUIT INSPECTION Proceed with diagnosis of each circuit in accordance with the inspection order c\
ofirmed in [6] and [7]. Deter-
mine whether the cause of the problem is in the sensor, actuators, wire harness and connectors, or the
ECU.
[9] ACTUATOR CHECK Check actuators for proper operation. Instructions for this diagnosis ar\
e given in the flow chart for each
circuit.
[10] REPAIRS After the cause of the problem is located, perform repairs by following the i\
nspection and replacement pro-
cedures in this manual.
[11] CONFIRMATION TEST
After completing repairs, confirm not only that the malfunction is elimi\
nated, but also perform diagnostic
code check and actuator check, etc. again to make sure the entire air condit\
ioning system is operating cor-
rectly.
AC±22
±
AIR CONDITIONING SYSTEM REPAIR INSTRUCTIONS
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CUSTOMER PROBLEM ANALYSIS CHECK SHEET
AC±24±
AIR CONDITIONING SYSTEM Troubleshooting
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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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DIAGNOSTIC CODE CHART
If a malfunction code is displayed during the diagnostic code check (sens\
or check), check the circuit listed for
that code in the table below (Proceed to the page given for that circuit.)\
Code No.Diag. Code Detecting Condition
00 Normal
11 *1 Open or short in room temperature sensor circuit.
12 Open or short in ambient temperature sensor circuit.
13 Open or short in evaporator temperature sensor circuit.
14*2 Open or short in water temperature sensor circuit.
21*3 Open in solar sensor circuit.
21*3
 Short in solar sensor circuit.
22*4
 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 c\
omparison to normal
operation.
23
 Open in pressure sensor circuit.
 Abnormal refrigerant pressure below 206 kPa (2.1 kgf/cm, 30 psi)
over 2,650 kPa (27 kgf/cm, 385 ps\
i)
31 Short to ground or power source circuit in Air Mix Damper position sens\
or circuit.
32 Short to ground or power source circuit in Air Inlet Damper position se\
nsor circuit.
33 Short to ground or power source circuit in Air Outlet Damper position s\
ensor circuit.
41 Air mix damper position sensor value does not change even if ECU operat\
es air mix servomotor.
42 Air inlet damper position sensor value does not change even if ECU oper\
ates air inlet servomotor.
43 Air outlet damper position sensor value does not change even if ECU ope\
rates air outlet
servomotor.
HINT: *1 If the room temp. is approx. ±20 °C (±4 °F) or lower, code 11 may be output even though the system
is normal.
*2 If the ambient temperature is approx. ±50 °C (±58 °F) or lower, a malfunction code may be output
even though the system is normal.
*3 If the check is being performed in a dark place, diagnostic code 21 (so\
lar sensor circuit abnormal) could be displayed.
In this case, perform diagnostic code check again while shining a light,\
such as an inspection light,
on the solar sensor.
If code 21 is still displayed, there could be trouble in the solar senso\
r circuit
AC±28
±
AIR CONDITIONING SYSTEM Troubleshooting
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