code 32 LEXUS SC300 1991 Service User Guide

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
WhereEverybodyKnowsYourName

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
WhereEverybodyKnowsYourName

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
WhereEverybodyKnowsYourName

HINT:
wThe buzzer sounds when the display code changes.
w Codes are displayed in order from the smaller to the
larger numbers.
w To cancel the check mode, press the OFF switch.
AC±30±
AIR CONDITIONING SYSTEM Troubleshooting
WhereEverybodyKnowsYourName

AC±44AC±46AC±48AC±50AC±52AC±54AC±56AC±58AC±60AC±62AC±64AC±66
MATRIX CHART OF PROBLEM SYMPTOMS
If a normal code is displayed during the diagnostic code check (sensor ch\
eck) but the trouble still occurs (reap-
pears), perform out troubleshooting for each problem symptom, checking the circuits for each symptom in the
order given in the table below (Proceed to the page given for each circuit)\
. AC±36
±
AIR CONDITIONING SYSTEM Troubleshooting
WhereEverybodyKnowsYourName

Check voltage between terminals TR
and SG of air conditioner assembly
connector.
Check room temperature sensor.
Check harness and connector between air
conditioner control assembly and room tem-
perature sensor (See page IN-27).
Check and repair air conditioner control
assembly. Proceed to next circuit inspection
shown on matrix chart (See page
AC-36
).However, when Diag. code
11 is displayed, check and replace
air conditioner control assembly.
Replace room temperature sensor.
Repair or replace harness or
connector.
CIRCUIT INSPECTION
Diag. Code 11Room Temperature Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the temperature inside the cabin and sends the appropria\
te signals the A/C control
assembly.
Code No.Diag. Code Detecting ConditionTrouble area
11
Open or short in room temperature sensor
circuit.
Room temperature sensor.

Harness or connector between room temp.
sensor and A/C control assembly.

A/C control assembly.
DIAGNOSTIC CHART
AC±44±
AIR CONDITIONING SYSTEM Troubleshooting
WhereEverybodyKnowsYourName

Check voltage between terminals TR and SG of air conditioner control
assembly connector.
(1) Remove console upper panel. (See page BO-111 )
(2) Remove A/C Control Assembly with connectors
still connected.
(3) Turn ignition switch ON.
Check voltage between terminals TAM and SG of air
conditioner control assembly connector at each tem-
perature.
Voltage
at 25°C (77°F) : 1.8~2.2 V
at 40°C (104°F) : 1.2~1.6 V
In addition, as the temperature increases, the
voltage decreases gradually.
Proceed to next circuit inspection shown on
matrix chart (See page AC-36).However,
when Diag. code 11 is displayed, check and
replace air conditioner control assembly.
Check room temperature sensor.
(1) Remove instrument finish lower No. 1 panel.
(See page Be-103).
Resistance
at 25°C (77°F) : 1.6~1.8k

at 50°C (122°F) : 0.5~0.7k

In addition, as the temperature increases, the
voltage decreases gradually.
Replace room temperature sensor.
Check for open and short in harness and connector between air conditioner
control assembly and room temperature sensor (See page IN-27).
Repair or replace harness or connector.
Check and repair air conditioner control
assembly.
(2) Disconnect room0 temperature sensor
connector.
Check voltage between terminals 1 and 2 of
room temperature sensor connector at each tem±
perature.
INSPECTION PROCEDURE
±
AIR CONDITIONING SYSTEM TroubleshootingAC±45
WhereEverybodyKnowsYourName

Diag. Code 12Ambient Temperature Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the ambient temperature and sends the appropriate signal\
s to the A/C control
assembly.
Code No.Diag. Code Detecting ConditionTrouble area
12
Open or short in ambient temperature sensor
circuit.
Ambient temperature sensor.

Harness or connector between ambient
temperature sensor and A/C control assem-
bly.

A/C control assembly.
DIAGNOSTIC CHART
Check voltage between terminals TAM and
SG of air conditioner control assembly con-
nector.
Check ambient temperature sensor.
Check harness and connector between air
conditioner control assembly and ambient
temperature sensor. (See page IN-27).
Check and replace air conditioner control
assembly.
Proceed to next circuit inspection
shown on matrix chart (See
pageAC-36 ). However, when Diag.
code 12 is displayed, check and re-
place air conditioner control assembly.
Replace ambient temperature
sensor.
Repair or replace harness or
connector.
AC±46±
AIR CONDITIONING SYSTEM Troubleshooting
WhereEverybodyKnowsYourName

Check voltage between terminals TAM and SG of air conditioner
control assembly connector.
(1) Remove console upper panel. (See page BO-111
(2) Remove A/C control assembly with
connectors still connected.
(3) Turn ignition switch ON.
Check voltage between terminals TAM and SG of air
conditioner control assembly connector at each tem-
perature.
at 25°C (77°F) : 1.35~1.75 V
at 40°C (104°F) : 0.85~1.25 V
In addition, as the temperature increases, the
voltage decreases gradually.
Proceed to next circuit inspection shown on
matrix chart (See page AC-36).However,
when Diag. code 11 is displayed, check and
replace air conditioner control assembly.
Check ambient temperature sensor.
(1) Remove under cover
(2) disconnect ambient temperature sensor connector.
Check resistance between terminals 1 and 2 of
ambient temperature sensor connector at each
temperature.
Resistance
at 25°C (77°F) : 1.6~1.8k

at 50°C (122°F) : 0.5~0.7k

In addition, as the temperature increases, the
voltage decreases gradually.
Replace ambient temperature sensor.
Check for open and short in harness and connector between air conditioner
control assembly and ambient temperature sensor (See page IN-27).
Repair or replace harness or connector.
Check and repair air conditioner control
assembly.
Voltage
INSPECTION PROCEDURE
±
AIR CONDITIONING SYSTEM TroubleshootingAC±47
WhereEverybodyKnowsYourName

Diag. Code 13Evaporator Temperature Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the temperature inside the cooling unit and sends the ap\
propriate signals to the air
conditioner control assembly.
Code No.Diag. Code Detecting ConditionTrouble area
13
Open or short in evaporator temperature sensor
circuit.
Evaporator temperature sensor.

Harness or connector between evaporator
temperature sensor and A/C control
assembly.

A/C control assembly.
DIAGNOSTIC CHART
Check voltage between terminals TE
and SG of air conditioner control as-
sembly
Check evaporator temperature sensor.
Check harness and connector between air
conditioner control assembly and evapora-
tor temperature sensor (See page IN-27).
Check and replace air conditioner control
assembly. 10Proceed to next circuit inspection
shown on matrix chart (See page
AC-36
). However, when Diag. code
13 is displayed, check and replace
air conditioner control assembly.
Replace evaporator temperature
sensor.
Repair or replace harness or
connector.
AC±48±
AIR CONDITIONING SYSTEM Troubleshooting
WhereEverybodyKnowsYourName