TOYOTA SUPRA 1995 Service Workshop Manual

INSPECTION PROCEDURE
AC±22).
Check and replace A/C amplifier.
Repair or replace harness or connector.
Check for open and short in harness and connector between A/C amplifier and air outlet damper control
servo motor, air outlet damper control servo motor and battery, air outlet damper control servo motor
and body ground (See page IN±26).
Replace air outlet servo motor.
Check air outlet damper control servo motor.
Proceed to next circuit inspection shown on matrix
chart (See page AC±26).
Actuator check.
Turn the temp. dial and check the condition of air flow.

The mode changes with the change in the tempera-
ture display as shown in the table.
The lever moves smoothly to DEF position.
The lever moves smoothly to FACE position.
Connect positive (+) lead to terminal 1 and negative
(±) lead to terminal 2.
Connect negative (±) lead to terminal 1 and positive
(1) lead to terminal 2.
1. Remove instrument panel.
2. Remove the air outlet damper control servo motor
assembly.
1. Set to the actuator check mode (see page AC±22).
2. Turn the temp. dial and change to step operation
.
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±51

Back Up Power Source Circuit
CIRCUIT DESCRIPTION
This is the back up power source for the A/C amplifier. Power is supplied even when the ignition switch is off
and is used for diagnostic sensor check memory, etc.
AC±52± AIR CONDITIONING SYSTEMTROUBLESHOOTING

INSPECTION PROCEDURE
Remove the A/C amplifier with connector still con-
ected.
Measure voltage between terminal + B of air condi-
tioner control assembly connector and body ground.
Voltage: Battery positive voltage
Proceed to next circuit inspection shown on matrix
chart (See page AC±26).

Remove ECU±B fuse from J/B No. 1.
Check continuity of ECU±B fuse.
Continuity
Check ECU±B fuse.
Check for short in all the harness and compo-
nents to the ECU±B fuse (See attached wiring
diagram).
Check voltage between terminal +B of A/C amplifier connector and
body ground.
Check and repair harness and connector between
A/C amplifier and battery.
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±53

IG Power Source Circuit
CIRCUIT DESCRIPTION
This is the power source for the A/C amplifier and servo motors, etc.
INSPECTION PROCEDURE
Remove the A/C amplifier with connector still con-
nected
Voltage: Battery positive voltage
1. Turn ignition switch ON.
2. Measure voltage between terminals IG and GND
of A/C amplifier.
Proceed to next circuit inspection shown on matrix
chart (See page AC±26).
Go to step
Check voltage between terminals IG and GND of A/C amplifier connector.
AC±54± AIR CONDITIONING SYSTEMTROUBLESHOOTING

Check continuity between terminal GND of A/C amplifier and body
ground.
Measure resistance between terminal GND of A/C
amplifier and body ground.
Remove HTR fuse from J/B No. 1.
Check continuity of HTR fuse.
Continuity
Check for short in all the harness and compo-
nents to the HTR fuse (See attached wiring
diagram).
Check and repair harness and connector between
A/C amplifier and battery.
Check HTR fuse.
Repair or replace harness or connector.
Resistance: O  continuity)
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±55

ACC Power Source Circuit
CIRCUIT DESCRIPTION
This circuit supplies power to the A/C amplifier.
AC±56± AIR CONDITIONING SYSTEMTROUBLESHOOTING

INSPECTION PROCEDURE
Check voltage between terminal ACC of A/C amplifier connector and
body ground.
Remove the A/C amplifier with connector still connected
Voltage: Battery positive voltage
1. Turn ignition switch To ACC.
2. Measure voltage between terminals ACC of A/C
amplifier connector and body ground.
Remove CIG fuse from J/B No. 1.
Check continuity of CIG fuse.
Continuity
Proceed to next circuit inspection shown on matrix
chart (See page AC±26).
Check CIG fuse.
Check for short in all the harness and compo-
nents to the CIG fuse (See attached wiring
diagram).
Check and repair harness and connector between
A/C amplifier and battery.
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±57

Heater Relay Circuit
CIRCUIT DESCRIPTION
The heater relay is switched on by signals from the A/C amplifier and switches power to the blower motor.
AC±58± AIR CONDITIONING SYSTEMTROUBLESHOOTING

Check voltage between terminal HR of A/C amplifier connector and
body ground.
Check heater relay.
Proceed to next circuit inspection shown on matrix
chart (See page AC±26).
Check HTR fuse.
Check and repair harness and connector between
A/C amplifier and battery.
Check for short in all the harness and compo-
nents to the HTR fuse (See attached wiring
diagram).
Replace heater relay.
Remove the A/C amplifier with connectors still con-
nected
Measure voltage between terminals HR of A/C ampli-
fier connector and body ground when ignition switch is
ON and OFF.
VoltageIgnition Switch
Check continuity between each pair of terminals of
heater relay shown below.
1. Apply battery positive voltage between terminals
1 and 3.
2. Check continuity between each pair of terminal
shown below.
Terminals 2 and 4
Terminals 4 and 5
No continuity
Continuity
Terminals 4 and 5
Terminals 1 and 3
Terminals 2 and 4
No continuity
Continuity
OFF
ON
OV
Blower OFF
Blower ON Below 1.O V
Battery positive
voltage
INSPECTION PROCEDURE
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±59

Blower Motor Circuit
CIRCUIT DESCRIPTION
This is the power source for the blower motor.
INSPECTION PROCEDURE
Check voltage between terminal BLW of A/C amplifier connector and
body ground.
Proceed to next circuit inspection shown on matrix
chart (See page AC±26).
Go to step
Remove the A/C amplifier with connector still con-
nected
Voltage: 1 ± 3 V
1. Turn ignition switch To ON.
2. Operate blower motor.
3. Measure voltage between terminals BLW of A/C
amplifier connector and body ground.
AC±60± AIR CONDITIONING SYSTEMTROUBLESHOOTING