Toyota ST185 Series Repair Manual page 152

* MEDIUM SPEED OPERATION (OPERATION AT MANUAL M1, M2)
WHEN THE BLOWER SW (A/C CONTROL ASSEMBLY) IS MOVED TO M1 POSITION, A SIGNAL IS INPUT FROM TERMINAL B3 OF A/C
CONTROL ASSEMBLY TO TERMINAL M1 OF A/C AUTO AMPLIFIER
THIS CAUSES TO CURRENT FLOWING TO TERMINAL HR OF THE A/C AUTO AMPLIFIER TO FLOW TO TERMINAL GND OF A/C AUTO
AMPLIFIER GROUND AND TURNS THE HEATER RELAY ON. SIMULTANEOUSLY, CURRENT FLOWING FROM TERMINAL BLW OF A/C
AUTO AMPLIFIER TO TERMINAL 3 OF A/C POWER TRANSISTOR
BLOWER MOTOR TO FLOW TO TERMINAL 5 OF HEATER RELAY
TERMINAL 1 OF POWER TRANSISTOR
SPEED.
IF THE BLOWER SW (A/C CONTROL ASSEMBLY) IS MOVED TO M2 POSITION, THE CURRENT FLOW FROM TERMINAL BLW OF THE
A/C AUTO AMPLIFIER TO TERMINAL 1 OF THE POWER TRANSISTOR BECOMES GREATER THAN FOR M1 AND CURRENT FLOWS
MORE EASILY BETWEEN TERMINAL 1 AND TERMINAL 2 OF THE POWER TRANSISTOR, SO THE BLOWER MOTOR ROTATES AT
MEDIUM HIGH SPEED.
* AUTO FUNCTION
WHEN THE AUTO SW (A/C CONTROL ASSEMBLY) IS SELECTED, THE CURRENT FLOW IS THE SAME FOR MED POSITION, BUT THE
A/C AUTO AMPLIFIER DECIDES THE APPROPRIATE AIR FLOW VOLUME ACCORDING TO THE SET TEMPERATURE AND TO INPUT
SIGNALS FROM EACH SENSOR. BY CONTROLLING THE CURRENT FLOW FROM TERMINAL BLW OF THE A/C AUTO AMPLIFIER TO
TERMINAL 3 OF POWER TRANSISTOR
STEPLESSLY.
3. OPERATION OF RECIRC/FRESH CONTROL SERVO MOTOR
(SWITCHING FROM FRESH TO RECIRC)
WITH IGNITION SW TURNED ON. THE CURRENT FLOWS FROM GAUGE FUSE TO TERMINAL 1 OF RECIRC/FRESH CONTROL SERVO
MOTOR. WHEN THE RECIRC/FRESH SW IS SWITCHED TO THE RECIRC SIDE, TO CURRENT FLOWS FROM TERMINAL 1 OF
RECIRC/FRESH CONTROL SERVO MOTOR
TERMINAL REC IND OF A/C AUTO AMPLIFIER
THE RECIRC SIDE.
WHEN IT IS IN THE RECIRC POSITION, THE CURRENT IS CUT INSIDE THE SERVO MOTOR AND THE DAMPER STOPS AT THAT
POSITION.
(SWITCHING FROM RECIRC TO FRESH)
WITH IGNITION SW ON, WHEN THE RECIRC/FRESH SW IS SWITCHED TO THE FRESH SIDE, THE CURRENT FLOWS FROM TERMINAL
1 OF RECIRC/FRESH CONTROL SERVO MOTOR
TERMINAL FRS IND OF AUTO A/C AMPLIFIER
THE FRESH SIDE. WHEN IT IS IN THE FRESH POSITION, THE CURRENT IS CUT INSIDE THE SERVO MOTOR AND THE DAMPER
STOPS AT THAT POSITION.
4. OPERATION OF AIR VENT MODE CONTROL SERVO MOTOR
WITH IGNITION SW TURNED ON, THE CURRENT FLOWS FROM GAUGE FUSE TO TERMINAL 5 OF AIR VENT MODE CONTROL SERVO
MOTOR TERMINAL 6 GROUND, AND THE DAMPER MOVES TO THE POSITION OF THE MODE SELECTION SW OF THE CONTROL
ASSEMBLY SWITCH IS ON.
WHEN THE MODE SELECTION SW OF A/C CONTROL ASSEMBLY IS MOVED TO DEF POSITION WITH THE DAMPER IN THE FACE
POSITION, THE CURRENT FLOWS FROM TERMINAL 7 OF AIR VENT MODE CONTROL SERVO MOTOR TO TERMINAL A25 OF A/C
CONTROL ASSEMBLY TERMINAL C10
AS A RESULT, THE SERVO MOTOR OPERATES UNTIL THE DAMPER REACHES DEF POSITION.
WHEN THIS OCCURS THE CURRENT TO THE A/C CONTROL ASSEMBLY IS SHUT OFF AND ROTATION OF THE MOTOR STOPS.
SWITCHING TO OTHER MODES IS CONTROLLED BY THE SERVO MOTOR ACCORDING THE FOLLOWING CURRENT:
1. FOOT/DEF POSITION : THE CURRENT FLOWS FROM TERMINAL 4 OF SERVO MOTOR TO TERMINAL A11 OF A/C CONTROL
ASSEMBLY.
2. FOOT POSITION : THE CURRENT FLOWS FROM TERMINAL 3 OF SERVO MOTOR TO TERMINAL A10 OF A/C CONTROL
ASSEMBLY.
3. BI–LEVEL POSITION : THE CURRENT FLOWS FROM TERMINAL 2 OF SERVO MOTOR TO TERMINAL A9 OF A/C CONTROL
ASSEMBLY.
5. OPERATION OF AIR MIX CONTROL SERVO MOTOR
WHEN THE TEMPERATURE CONTROL VOLUME IS TURNED TO THE COOL SIDE, A SIGNAL IS INPUT TO TERMINAL TEST OF A/C
AUTO AMPLIFIER FROM TERMINAL A21 OF A/C CONTROL ASSEMBLY.
AS A RESULT, A SIGNAL IS OUTPUT FROM TERMINAL AMH OF A/C AUTO AMPLIFIER TO TERMINAL 3 OF A/C SYSTEM AMPLIFIER
AND THE CURRENT FLOWING TO TERMINAL 7 OF A/C SYSTEM AMPLIFIER FROM THE GAUGE FUSE FLOWS FROM TERMINAL 1 OF
A/C SYSTEM AMPLIFIER
TERMINAL 9 GROUND. CAUSING THE AIR MIX CONTROL SERVO MOTOR TO ROTATE.
AT THIS TIME IS INPUT THE DAMPER OPENING ANGLE FROM TERMINAL 4 OF SERVO MOTOR TO TERMINAL TP OF A/C AUTO
AMPLIFIER THIS IS USED TO DETERMINE THE DAMPER STOP POSITION AND MAINTAIN THE SET TEMPERATURE.
WHEN THE TEMPERATURE CONTROL VOLUME IS TURNED TO THE WARM SIDE, IN A/C SYSTEM AMPLIFIER THE CURRENT FLOWS
FROM SERVO MOTOR TERMINAL 6 OF A/C SYSTEM AMPLIFIER
TERMINAL 2 TERMINAL 1 OF A/C SYSTEM AMPLIFIER
SWITCHING THE DAMPER FROM COOL TO WARM SIDE.
TERMINAL 2
TERMINAL 2
TERMINAL 2
TERMINAL GND
TERMINAL 3
TERMINAL GND
GROUND.
TERMINAL 2 OF AIR MIX CONTROL SERVO MOTOR
TERMINAL 2 GROUND CAUSES CURRENT FLOWING TO THE
TERMINAL 4 TERMINAL 2 OF BLOWER MOTOR
GROUND, CAUSING TO BLOWER MOTOR ROTATE AT MEDIUM LOW
GROUND, THE A/C AUTO AMPLIFIER CONTROLS THE BLOWER MOTOR
TERMINAL A18 OF A/C CONTROL ASSEMBLY
GROUND, THE MOTOR ROTATES AND THE DAMPER MOVES TO
TERMINAL A19 OF A/C CONTROL ASSEMBLY
GROUND, THE MOTOR ROTATES AND THE DAMPER MOVES TO
TERMINAL 6
TERMINAL 6 OF AIR MIX CONTROL SERVO MOTOR
TERMINAL 9 GROUND, ROTATING THE MOTOR IN REVERSE AND
TERMINAL 1
TERMINAL B5
TERMINAL B1
IF A/C SYSTEM AMPLIFIER
MOTOR
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