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8. Ventilation Fan Motor Circuit
Microcomputer
VENTILATION
44
DIFECTION
VENTILATION
40
FAN OUTPUT
CN11
Voltage waveform
0V
When T2
When T1
0V
Ventilation fan motor is a 12V DC motor. It operates by inputting DC12V power (K-12V) and ventilation fan PWM signal to
①
③
CN11
pin and CN11
(K-12V) is generated from DC-DC converter of the ventilation fan motor circuit. It is the power source exclusively for the
ventilation fan motor and is independent from 12V of the power circuit for control.
Ventilation fan PWM signal (Microcomputer
converted into analog voltage inside the ventilation fan motor to operate it.
If width of PWM signal is made wider, analog voltage becomes higher and the motor rotation speed becomes faster, as
shown in Fig. 8-2.
When the motor is rotating normally, the ventilation abnormality detection signal is Lo (approximately 0V). In the event that
the fan is locked or unable to rotate due to failure, "Hi" ventilation abnormality detection signal (approximately 5V) is output
(Microcomputer
pin) to show abnormality.
When the Microcomputer receives this signal, it suspends ventilation fan PWM signal and outputs the same signal again
after 30 seconds have elapsed. If the abnormality continues and retry is repeated 5 times within 3 minutes since the first
abnormality detection, abnormality is judged and two way air exchange lamp blinks (lit for 4 seconds and off for 1 second).
0V
③
pin
T1
T2
Convert to analog voltage at the ventilation
fan motor internal circuit.
pin respectively and outputting ventilation abnormality detection signal from CN11
pin) is a command instruction to the ventilation fan motor. This signal is
5V
R934
Fig. 8-1
T1: Low-speed rotation
T2: High-speed rotation
Fig. 8-2
- 43 -
K-12V
CN11
1
2
3
4
M
④
pin.
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