relay TOYOTA SUPRA 1995 Service Repair Manual

HINT:
wIf the instruction ºProceed to next circuit inspection shown on matrix chart is given in the flow chart
for each circuit, proceed to the circuit with the next highest number in the table to continue the check.
wIf the trouble still reappears even though there are no abnormalities in any of the other circuits, then
check or replace the A/C amplifier.
AC±52
AC±54
AC±56
AC±58
AC±60
AC±62
AC±66
AC±69
IN±35
AC±71
AC±76
AC±77
AC±107
AC±92
AC±91
AC±95
AC±96
AC±98
AC±97
IG power source circuitBackup power source
circuitACC power source circuitHeater relay circuitCompressor circuitBlower motor circuitA/C amplifierTemperature set dial circuitA/C control assembly circuitRefrigeration system inspection
with manifold gauge setElectric cooling fanWater valveDrive belt tensionRefrigerant volumeCondenserExpansion valveEvaporatorHeater radiatorReceiver
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±27

Blinking Light FRS Pressure Switch Circuit
CIRCUIT DESCRIPTION
The pressure switch sends the appropriate signals to the A/C amplifier when the air conditioning refrig-
erant pressure drops too low or rises too high. When the A/C amplifier receives these signals, it outputs
signals via the ECM to switch OFF the compressor relay and turns the magnetic clutch OFF.
Diagnostic Sensor Check Detecting ConditionTrouble Area

Pressure switch

Harness or connector between pressure switch
and A/C amplifier

Refrigerant pipe line

A/C amplifierOpen 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)
AC±40± AIR CONDITIONING SYSTEMTROUBLESHOOTING

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

(See page AC±99).
Check blower motor.
Go to step
Replace blower motor.
Check blower motor control relay.
Replace blower motor control relay.
Repair or replace harness or connector
Remove blower motor control relay with connectors
still connected
1. Turn ignition switch To ON.
2. Operate blower motor.
TerminalsStandard Value
Continuity
Battery Positive
Voltage
Battery Positive
Voltage
Battery Positive
Voltage
Connect positive (+) lead to terminal 2
of blower motor connector, negative (±) lead to
terminal 1.
Remove blower motor control (see page AC±99).
Blower motor operates smoothly.
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±61

Compressor Circuit
CIRCUIT DESCRIPTION
The A/C amplifier outputs the magnetic clutch ON signal from terminal MGC to the ECM. When the ECM re-
ceives this signal, it sends a signal from terminal ACMG and switches the air conditioning magnetic clutch relay
ON, thus turning the air conditioning compressor magnetic clutch ON.
AC±62± AIR CONDITIONING SYSTEMTROUBLESHOOTING

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

Remove magnetic clutch relay from R/B No. 2.
Check continuity between each pair of terminals
shown below of magnetic clutch relay.
Terminals 1 and 2
Terminals 3 and 5
Terminals 3 and 5
No continuity
Continuity
Replace magnetic relay.
Check and replace the ECM.
Repair or replace harness or connector.
A/C SwitchVoltage
ON
OFF
Check for open and short in harness and connector between the ECM and
battery (See page IN±30).
Approx. 1.3. V
Approx. 75

Battery positive voltage
Check magnetic clutch relay.
Check voltage between terminal ACMG of ECM and body ground.
1. Apply battery positive voltage between terminals
1 and 2.
2. Check continuity between terminals 3 and 5.
1. Remove the ECM with connectors still con
nected.
2. Turn ignition switch on.
1. Turn fan speed control dial (Lo, Med or Hi).
2. Measure voltage between terminal ACMG of the
ECM connector and body ground.
Proceed to next circuit inspection shown on matrix
chart (See page AC±26).
~ 1.3 V
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±65

1. REMOVE AIR INLET SERVOMOTOR
(a) Disconnect the connector.
(b) Disconnect the control link.
(c) Remove the 3 screws and the air inlet servomotor.
2. REMOVE BLOWER MOTOR CONTROL RELAY
(a) Disconnect the connector.
(b) Remove the 3 screws and the blower motor control relay.
3. REMOVE BLOWER MOTOR
(a) Disconnect the connector.
(b) Using a torx driver, remove the blower motor.
4. REMOVE EVAPORATOR
(a) Remove the A/C unit wire harness.
(b) Remove the foot air duct.
(c) Remove the A/C unit block joint.
(d) Remove the 6 screws and down and the lower cover.
(e) Remove the 4 screws and the evaporator cover.
(f) Pull out the evaporator.
(g) Pull out the evaporator sensor from the evaporator.
(h) Using a hexagon wrench, remove the 2 bolts and separate
the evaporator and expansion valve.
Torque: 5.4 NVm (55 kgfVcm, 48 in.Vlbf)
INSTALLATION HINT: If the evaporator was replaced, add
compressor oil to the compressor.
Add 40 cc (1.4 fl.oz)
Compressor oil
ND±OIL 8 or equivalent
± AIR CONDITIONING SYSTEMAIR CONDITIONING UNITAC±83

BLOWER MOTOR CONTROL RELAY
BLOWER MOTOR CONTROL RELAY
REMOVAL
1. REMOVE BLOWER MOTOR
(See page AC±82)
2. REMOVE BLOWER MOTOR CONTROL RELAY
(a) Disconnect the connector.
(b) Remove the 3 screws and the blower motor control relay.
BLOWER MOTOR CONTROL RELAY
INSPECTION
(See page AC±61)
BLOWER MOTOR CONTROL RELAY
INSTALLATION
Installation is in the reverse order of removal. AC±100
± AIR CONDITIONING SYSTEMBLOWER MOTOR CONTROL RELAY