engine TOYOTA SUPRA 1995 Service Repair Manual

CAUTION:
wBe sure to connect both the high and low pressure
quick±connectors onto the A/C system when evacuating.
If only one side is connected, the system would be open
to atmosphere through the other connector, making it
impossible to maintain vacuum.
wBe sure to turn off the manifold gauge valve immediately
after evacuating the system. Then you may switch off the
vacuum pump.
PRECAUTIONS WHEN CHARGING
REFRIGERANT
1. DO NOT OPERATE COMPRESSOR WITHOUT ENOUGH
REFRIGERANT IN REFRIGERANT SYSTEM
If there is not enough refrigerant in the refrigerant system, oil
lubrication will be insufficient and compressor burnout may
occur, so take care to avoid this.
2. DO NOT OPEN HIGH PRESSURE MANIFOLD VALVE
WHILST COMPRESSOR IS 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 SYSTEM WITH
REFRIGERANT
If refrigerant is overcharged, it causes problems such as in-
sufficient cooling, poor fuel economy, engine overheating
etc.
SUPPLEMENTAL RESTRAINT SYSTEM
(SRS)
Failure to carry out service operations in the correct se-
quence could cause the supplemental restraint system to
deploy, possibly leading to a serious accident.
During 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 RS section before carrying
out operation. AC±6
± AIR CONDITIONING SYSTEMGENERAL DESCRIPTION

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

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

A/C amplifier

Ambient temp. sensor
Harness or connector between ambient temp. sensor and A/C amplifier

A/C amplifier

Evaporator temp. sensor
Harness or connector between evaporator temp. sensor and A/C amplifier

A/C amplifier

Engine coolant temp. sensor
Harness or connector between coolant temp. sensor and A/C amplifier

A/C amplifier

Solar sensor
Harness or connector between sensor and A/C amplifier

A/C amplifier

Compressor drive belt
Compressor lock sensor
Compressor
Harness and connector between A/C amplifier and compressor, compressor
lock sensor

A/C amplifier

Pressure switch
Harness or connector between pressure switch and A/C amplifier

Refrigerant pipe line
A/C amplifier

Air mix damper position sensor
A/C amplifier
Harness or connector between air mix damper position sensor and A/C amplifier

Air outlet damper position sensor
A/C amplifier
Harness or connector between max cool damper position sensor and A/C amplifi-
er

Air mix damper control servo motor
Air mix damper position sensor
Harness and connector between A/C amplifier and air mix position sensor

Harness and connector between A/C amplifier and air mix damper controlservo motor
A/C amplifier

Air outlet damper control servo motor
Air outlet damper position sensor
Harness and connector between A/C amplifier and air outlet position sensor

Harness and connector between A/C amplifier and air outlet damper motor
A/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

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

Blinking Light F D Engine Coolant Temperature Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the coolant temperature and sends the appropriate signals to the A/C amplifier.
These signals are used for warm up control when the engine is cold.
Diagnostic Sensor Check Detecting ConditionTrouble Area
Open or short in engine coolant temperature sensor
circuit.
Engine coolant temperature sensor

Harness or connector between engine coolant
temperature sensor and A/C amplifier

A/C amplifier
AC±34± AIR CONDITIONING SYSTEMTROUBLESHOOTING

INSPECTION PROCEDURE
(See page AC±26).
(See page IN±30)
Check voltage between terminals TW and SG of A/C amplifier connector.
Proceed to next circuit inspection shown on matrix
chart (See page AC±26). However, if the light is still
blinking, check and replace A/C amplifier.
Check engine coolant temperature sensor.
Replace engine coolant temperature sensor.
Check harness and connector between A/C amplifier and engine coolant
temperature sensor (See page
IN±30).
Repair or replace harness or connector.
Check and replace A/C amplifier.
Remove A/C amplifier with connectors still con-
nected.
1. Turn ignition switch ON.
2. Measure voltage between terminal TW of SG
of A/C amplifier connector at each temperature.
HINT: As the temperature increases, the voltage decreases
gradually.
Voltage:
at 0°C (32°F): 2.8 ~ 3.2 V
at 40°C (104°F): 1.8 ~ 2.2 V
at 70°C (158°F): 1.3 ~ 1.5 V
1. Remove A/C unit (See page AC±80).
2. Remove engine coolant temperature sensor.
Measure resistance between terminals 1 and 2 of en-
gine coolant temperature sensor connector at each
temperature.

HINT: As the temperature increases, the resistance
decreases gradually.
Resistance:
at 0°C (32°F): Below 50 k

at 40°C (104°F): 2.4 ~ 2.8 k

at 100°C (212°F): Over 0.2 k

± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±35

Blinking Light A C Compressor Lock Sensor Circuit
CIRCUIT DESCRIPTION
This sensor sends 1 pulse per engine revolution to the A/C amplifier. If the number ratio of the compres-
sor speed divided by the engine speed is smaller than a predetermined value, the A/C amplifier turns
the compressor off. And, the indicator flashes at about 1 second intervals.
Diagnostic Sensor Check Detecting ConditionTrouble Area

Compressor
Compressor drive belt

Compressor lock sensor

Harness and connector between compressor and
A/C amplifier

A/C amplifierAll conditions below are detected for 3 secs. or more
(a) Engine speed: 450 rpm or more
(b) Ratio between engine and compressor speed
deviates 20% or more in comparison to normal
operation.
AC±38± AIR CONDITIONING SYSTEMTROUBLESHOOTING

INSPECTION PROCEDURE
(See page AC±26).
(See page IN±30).
Repair or replace harness or connector.
Replace compressor lock sensor.
Check for open and short harness and connector between A/C amplifier
and room temperature sensor (See page
IN±30).
Check compressor lock sensor.
Check compressor.
Adjust drive belt tension or repair compressor.
Proceed to next circuit inspection shown on matrix
chart (See page AC±26). However, if the light is still
blinking, check and replace A/C amplifier.
Disconnect compressor lock sensor connector
Measure resistance between terminals 1 and 2 of
compressor lock sensor connector.
Resistance: at 20°C (68°F): 160 ~ 210

(1) Check compressor drive belt tension.
(2) Check the compressor does not lock during operation with engine started and blower
switch
and A/C switch ON.
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±39

(See page IN±30).
AC±22).
Actuator check.
Check and replace A/C amplifier.
Check harness and connector between A/C amplifier and air mix damper control ser-
vo motor assembly (See page IN±30).
Repair or replace harness or connector.
Replace air mix damper control servo motor
assembly.
Check air mix damper control servo motor.
Proceed to next circuit inspection shown on matrix
chart (See page AC±26).
Remove air mix damper control servo motor assem-
bly
The lever turns smoothly to Cool side.
The lever turns smoothly to Hot side.
Turn the TSET dial and check the operation of the air
mix damper and the condition of the blower.
Set Temp.Air Mix DamperCondition
Connect negative (±) lead to terminal 2 and positive
(+) lead to terminal 1.
Connect positive (+) lead to terminal 2 and negative
(±) lead to terminal 1.
1. Warm up the engine.
2. Set to the actuator check mode (See page AC±22)
3. Turn the TSET dial and change it to step operation.
Cool air comes out
Warm air comes out
0% (Fully closed)
100% (Fully opened)
Below 20
Over 23
20 ~ 2350%
INSPECTION PROCEDURE
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±45

Check voltage between terminal A/C IN of A/C amplifier connector and
body ground.
Check air conditioning compressor magnetic clutch.
Go to step
Check for open and short in harness and connector between air
conditioner compressor and magnetic clutch relay (See page IN±30).
Repair or replace harness or connector.
Go to step
1. Remove A/C amplifier with connectors still con
nected.
2. Start the engine.
Check voltage between terminal A/C IN of A/C amplifi-
er connector and body ground when magnetic clutch is
on and off by A/C switch.
Magnetic ClutchVoltage
ON
OFF Below 1 V
Connect positive (+) lead connected to battery to
magnetic clutch connector terminal 4.
Disconnect magnetic clutch connector.
Magnetic clutch is energized.
Repair air conditioning compressor magnetic
clutch.
10 ± 14 V
INSPECTION PROCEDURE
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±63