●
Example
p
2
When the temperature in the vehicle is higher than the set
temperature.
When the temperature in the vehicle is high, in-vehicle sen-
sor resistance is small and the input voltage to the auto
amplifier becomes small. As a result, the voltage from the air
mix door position arithmetic circuit also becomes small.
When this voltage is smaller than the voltage from the PBR,
comparator (2), Tr
p
2
and Tr
p
3
turn ON.
Accordingly terminal No.
p
13
becomes
!
and terminal No.
p
12
becomes
@
. The air mix door motor rotates counterclock-
wise and the air mix door moves toward the “COLD” side.
As the air mix door moves toward the “COLD” side, the volt-
age from the PBR becomes smaller and consequently
becomes equal to that from the air mix door position arith-
metic circuit. As a result, comparator (2) turns OFF and the
air mix door motor stops.
AIR MIX DOOR MOTOR
The air mix door motor is attached to the heater unit. It rotates
so that the air mix door is opened to a position set by the auto
amplifier. Motor rotation is conveyed through a shaft. The air mix
door position is then fed back to the auto amplifier by the PBR
built into the air mix door motor.
SHA569CB
Auto amp.
Comparator
(1)
Air mix door
position
arithmetic
circuit
PBR
Comparator
(2)
Air mix
door
motor
SHA570CB
Auto amp.
Comparator
(1)
Air mix door
position
arithmetic
circuit
PBR
Comparator
(2)
Air mix
door
motor
KHA127
Air mix door link
Air mix door lever
Air mix door motor
Heater unit
SYSTEM DESCRIPTION
AUTO
Control System Output Components (Cont’d)
HA-93