1995 TOYOTA SUPRA sensor

INSPECTION PROCEDURE
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.
(See page IN±30).(See Page IN±30).
Remove A/C amplifier with connectors still con-
nected.
Check voltage between terminals TR and SG of A/C amplifier connector.
Check room temperature sensor.
Check harness and connector between A/C amplifier and room
temperature sensor (See page
IN±30).
Replace room temperature sensor.
Repair or replace harness or connector.
Check and replace A/C amplifier.
1. Turn ignition switch ON.
2. Measure voltage between terminal TR of SG
of A/C amplifier connector at each temperature.
1. Remove instrument panel.
2. Disconnect room temperature sensor connector.
Check resistance between terminals 1 and 2 of room
temperature sensor connector.

Resistance:
at 25°C (77°F): 1.6 ~ 1.8 k

HINT: As the temperature increases, the voltage decreases
gradually.
Voltage:
at 25°C (77°F): 1.8 ~ 2.2 V
at 40°C (104°F): 1.2 ~ 1.6 V
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±29

CIRCUIT DESCRIPTION
This sensor detects the ambient temperature and sends the appropriate signals to the A/C amplifier.
Diagnostic Sensor Check Detecting Condition
Open or short in ambient temperature sensor circuit.
Trouble Area

Ambient temperature sensor

Harness or connector between ambient tempera±
ture sensor and A/C amplifier

A/C amplifier
Blinking Light B L Ambient Temperature Sensor Circuit
AC±30± AIR CONDITIONING SYSTEMTROUBLESHOOTING

(See page AC±26)
(See page IN±30).
Check voltage between terminals TAM and SG of A/C amplifier connector.
Check ambient temperature sensor.
Check harness and connector between A/C amplifier and ambient
temperature sensor (See page
IN±30).
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 and replace A/C amplifier.
Repair or replace harness or connector.
Replace ambient temperature sensor.
Remove A/C amplifier with connectors still con-
nected.
1. Turn ignition switch ON.
2. Measure voltage between terminal TAM of SG
of A/C amplifier connector at each temperature.
HINT: As the temperature increases, the voltage decreases
gradually.
Voltage:
at 25°C (77°F): 1.35 ~ 1.75 V
at 40°C (104°F): 0.85 ~ 1.25 V
1. Remove the clip and the sensor from the right
side inside the bumper reinforcement.
2. Disconnect ambient temperature sensor connec±
tor.
Check resistance between terminals 1 and 2 of ambi-
ent temperature sensor connector at each tempera-
ture.

Resistance:
at 25°C (77°F): 1.6 ~ 1.8 k

at 50°C (122°F): 0.5 ~ 0.7 k

HINT: As the temperature increases, the resistance
decreases gradually.
NOTICE:
When installing the ambient temperature sensor,
be sure to connect the sensor connector before
connecting the battery.
INSPECTION PROCEDURE
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±31

Blinking Light FOOT Evaporator Temperature Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the temperature inside the cooling unit and sends the appropriate signals to the
A/C amplifier.
Diagnostic Sensor Check Detecting ConditionTrouble Area
Open or short in evaporator temperature sensor
circuit.
Evaporator temperature sensor

Harness or connector between evaporator
temperature sensor and A/C amplifier

A/C amplifier
AC±32± AIR CONDITIONING SYSTEMTROUBLESHOOTING

INSPECTION PROCEDURE
(See page AC±26).
(See page IN±30)
Check voltage between terminals TE and SG of A/C amplifier connector.
Check and replace A/C amplifier.
Repair or replace harness or connector.
Replace evaporator temperature sensor.
Check harness and connector between A/C amplifier and evaporator
temperature sensor (See page
IN±30).
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 evaporator temperature sensor.
Remove A/C amplifier with connectors still con-
nected.
1. Turn ignition switch ON.
2. Measure voltage between terminal TE 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): 2.0 ~ 2.4 V
at 15°C (59°F): 1.4 ~ 1.8 V
Check resistance between terminals 1 and 2 of evapo-
rator temperature sensor connector at each tempera-
ture.

Resistance:
at 0°C (32°F): 4.5 ~ 5.2 k

at 15°C (59°F): 2.0 ~ 2.7 k

HINT: As the temperature increases, the resistance
decreases gradually.

Remove evaporator temperature sensor (See page
AC±106)
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±33

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 DEF Solar Sensor Circuit
CIRCUIT DESCRIPTION
A photo diode in the solar sensor detects solar radi±
ation and sends signals to the A/C amplifier.
Diagnostic Sensor Check Detecting ConditionTrouble Area

Solar sensor

Harness or connector between solar sensor and
A/C amplifier

A/C amplifierOpen or short in solar sensor circuit.
Please not that blinking of the LED for DEF is not
abnormal when the sensor is not receiving solar
radiation.
AC±36± AIR CONDITIONING SYSTEMTROUBLESHOOTING