Page 16 of 2543
PANEL DIAGNOSIS SYSTEM
If a trouble occurs in A/C system, the specified lamp on the control panel starts blinking during the diagnos-
tic sensor check.
During system diagnosis, a trouble is indicated on the panel by the blinking of a specified light instead of
a code display. (See TROUBLE CODE CHART)
For example, when a trouble occurs in solar sensor circuit, the LED for DEF mode switch will be blinking
during the diagnostic sensor check.
SWITCH
SWITCH NAMECODECODESWITCH NAMECODESWITCH NAME
LED
INDICATOR NAMECODEINDICATOR NAMECODEINDICATOR NAMECODE
AC±16± AIR CONDITIONING SYSTEMTROUBLESHOOTING
Page 17 of 2543
Warning for A/C compressor lock
If compressor lock occurs during air conditioning operation,
the [A/C] switch indicator on the air conditioning control as-
sembly starts blinking.
When this occurs, check for compressor lock using panel
diagnosis check then proceed to inspect the circuit or the
component.
Compressor lock sensor circuit " page AC±38
LIST OF OPERATION METHODS
By operating each of the air conditioning control switches as shown in the diagram below, it is possible to
enter the diagnosis check mode.
Indicator Check
Diagnostic
Sensor Check
(continuous operation)
Diagnostic
Sensor Check
(stepped operation)
Cancel check mode and can start
conditioning control
Actuator Check
(continuous
operation)
Turn ignition switch ON with AUTO and
switches held down.
If both Auto switch and switch are
not pressed at the same time.
: Indicates a switch operation
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±17
Page 18 of 2543
INDICATOR CHECK
1. Turn the ignition switch on while pressing the air conditioning
control AUTO switch and R/F SW simultaneously.
2. Check that all the indicators light up and go off at 1
second intervals 4 times in succession.
HINT:
wAfter the indicator check is ended, the diagnostic sensor
check begins automatically.
wPress the OFF switch when cancelling the check mode.
DIAGNOSTIC SENSOR CHECK
1. Perform an indicator check. After the indicator check is
completed, the system enters the diagnostic sensor check
mode automatically.
2. Check the LED blinking on the panel. Refer to the list of codes
on page AC±20 when translating the trouble code from the
LED blinking.
If the slower display is desired, press the RDEF switch and
change it to step operation. Each time the RDEF switch is
pressed, the blinking LED changes by 1 step.
CLEARING TROUBLE CODES' MEMORY
Method 1:
1. Pull out the ECU±B fuse in Junction Block No. 1 for 10 sec.
or longer to clear the trouble codes' memory.
2. After reinserting the fuse, check that the normal code is
output.
Method 2:
Press the RDEF switch while pushing the A/C switch during
the sensor check mode. AC±18
± AIR CONDITIONING SYSTEMTROUBLESHOOTING
Page 20 of 2543
SENSOR CHECK TROUBLE CODE CHART
If a LED is blinking during the diagnostic sensor check, check the circuit listed for the code in the table below
(Proceed to the page given for that circuit.)
No.
Blinking LED
Detecting Condition
0 L±AUTO Normal
1 L±FACE*1 Open or short in room temperature sensor circuit.
2 L±B/L Open or short in ambient temperature sensor circuit.
3 L±FOOT Open or short in evaporator temperature sensor circuit.
4 L±F/D*2 Open or short in engine coolant temperature sensor circuit.
5
L DEF*3 Open in solar sensor circuit.
5 L±DEF*3 Short in solar sensor circuit.
6
L±A/C*4
All conditions below are detected for 3 secs. or more.
(a) Engine speed 450 rpm or more.
(b) Ratio between engine and compressor rpm deviates 20% or more in comparison to normal operation.
7
L±FRS
Open in pressure sensor circuit.
Abnormal refrigerant pressure [ below 196 kPa (2.0 kgf/cm2, 28 psi)
over 3,140 kPa (32.0 kgf/cm2, 455 psi) ]
8
L±REC
Short to ground or power source circuit in air mix damper position sensor circuit.
9 L±LO Short to ground or power source circuit in air outlet damper position sensor circuit.
10 L±M2 Air mix damper position sensor value does not change even if A/C amplifier signals the
air mix damper control servo motor to operate.
11
L±HI
Air outlet damper position sensor value does not change even if A/C amplifier signals the
air outlet damper control servo motor to operate.
HINT: *1If the room temp. is approx. ±20°C (±4°F) or lower, FACE light may blink even though the
system is normal.
*
2If the ambient temperature is approx. ±50°C (±58°F) or lower, the B/L light may blink even
though the system is normal.
*
3If the check is being performed in a dark place, the LED for DEF (solar sensor circuit abnormal)
could be blinking.
In this case, perform diagnostic sensor check again while shining a light, such as an inspection
light, on the solar sensor.
If the light is still blinking, there could be trouble in the solar sensor circuit. AC±20
± AIR CONDITIONING SYSTEMTROUBLESHOOTING
Page 21 of 2543
AC±28
AC±30
AC±32
AC±34
AC±36
AC±38
AC±40
AC±42
AC±48
AC±42
AC±44
AC±48
AC±50
Trouble AreaMemory*5See page
(8.5 min. or more)
(8.5 min. or more)
(8.5 min. or more)
(8.5 min. or more)
(8.5 min. or more)
(1 min. or more)
(1 min. or more)
(15 secs. or more)
(15 secs. or more)
Room temp. sensorHarness or connector between room temp. sensor and A/C amplifier
A/C amplifier
Ambient temp. sensorHarness or connector between ambient temp. sensor and A/C amplifier
A/C amplifier
Evaporator temp. sensorHarness or connector between evaporator temp. sensor and A/C amplifier
A/C amplifier
Engine coolant temp. sensorHarness or connector between coolant temp. sensor and A/C amplifier
A/C amplifier
Solar sensorHarness or connector between sensor and A/C amplifier
A/C amplifier
Compressor drive beltCompressor lock sensorCompressorHarness and connector between A/C amplifier and compressor, compressor
lock sensor
A/C amplifier
Pressure switchHarness or connector between pressure switch and A/C amplifier
Refrigerant pipe lineA/C amplifier
Air mix damper position sensor A/C amplifierHarness or connector between air mix damper position sensor and A/C amplifier
Air outlet damper position sensor A/C amplifierHarness or connector between max cool damper position sensor and A/C amplifi-
er
Air mix damper control servo motorAir mix damper position sensorHarness and connector between A/C amplifier and air mix position sensor
Harness and connector between A/C amplifier and air mix damper controlservo motorA/C amplifier
Air outlet damper control servo motor Air outlet damper position sensorHarness and connector between A/C amplifier and air outlet position sensor
Harness and connector between A/C amplifier and air outlet damper motorA/C amplifier
HINT: *4Compressor lock (A/C light blink) is indicated only for a current malfunction. (See page AC±38)
To confirm the trouble indication, perform the following steps.
(1) With the engine ON, enter the trouble code check mode.
(2) Press the R/F switch to enter actuator check mode, and set the operation to Step No. 3.
(3) Press the AUTO switch to return to diagnostic sensor check mode.
(4) The A/C light starts to blink after approx. 3 secs.
*
5The A/C amplifier memorizes the trouble code of the respective malfunction when it occurs
for period of time indicated in the brackets.
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±21
Page 22 of 2543
Step No.
Conditions
Blower
MotorAir Flow
ventAir Inlet
damper
Set
Temperature
°C (°F)
Magnetic
clutchAir mix
damper
ACTUATOR CHECK
1. After entering the sensor check mode, press the R/F switch.
2. Turn the temperature set dial and change it to step operation.
Each time the dial is turned, the actuator operation changes
by 1 step.
HINT:
wCheck the change of actuator operation visually and by
hand.
wTo cancel the check mode, press the OFF switch. AC±22
± AIR CONDITIONING SYSTEMTROUBLESHOOTING
Page 26 of 2543
MATRIX CHART OF PROBLEM SYMPTOMS
If a normal code is displayed during the diagnostic sensor check but the trouble still occurs, perform trouble-
shooting 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±28
AC±30
AC±32
AC±34
AC±36
AC±38
AC±40
AC±42
AC±44
AC±46
AC±48
AC±50See page
Suspect Area
Symptom
Whole functions of the A/C system does not operate.
No blower operation
No blower control
Insufficient air flow
No cool air comes out
No warm air comes out
Output air is warmer or colder than the set
temperature or response is slow
No temperature control
(only Max. cool or Max. warm)
No air inlet control
No air outlet control
Engine idle up does not occur, or is continuous
Blinking of A/C indicator
Trouble code not recorded.
Set mode is cleared when IG switch is turned off.
Temperature Control
Air Flow Control
Room temp. sensor circuitAmbient temp. sensor
circuitEvaporator temp. sensorcircuitSolar sensor circuitEngine coolant temp. sensor
circuitPressure switch circuitAir mix damper positionsensor circuitAir mix damper controlservo motor circuitAir inlet damper controlservo motor circuitAir outlet damper controlservo motor circuitCompressor lock sensorcircuitAir outlet damper positionsensor circuit
AC±26± AIR CONDITIONING SYSTEMTROUBLESHOOTING
Page 28 of 2543
CIRCUIT INSPECTION
Blinking Light FACE Room Temperature Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the temperature inside the cabin and sends the appropriate signals to the A/C am-
plifier.
Diagnostic Sensor Check Detecting Condition
Open or short in room temperature sensor circuit.
Trouble Area
Room temperature sensor
Harness or connector between room temperature
sensor and A/C amplifier
A/C amplifier
AC±28± AIR CONDITIONING SYSTEMTROUBLESHOOTING
![TOYOTA SUPRA 1995 Service Repair Manual Warning for A/C compressor lock
If compressor lock occurs during air conditioning operation,
the [A/C] switch indicator on the air conditioning control as-
sembly starts blinking.
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If compressor lock occurs during air conditioning operation,
the [A/C] switch indicator on the air conditioning control as-
sembly starts blinking.
When this occurs, ch")
