– 55 –
10. Temporary Switch
● The temporary switch is used to operate the air conditoner temporarily when the wireless remote control
is lost or faulty.
● The air conditioner operates in the previous mode at the previously set temperature. However, when the
power switch is set to OFF, it starts automatic operation.
Fig. 10-1
11. DC Fan Motor Drive Circuit
● Fig. 11-1 shows the indoor DC fan motor drive circuit.
Fig. 11-1
● The circuit produces the fan motor drive voltages, 8-33V, from 35V DC supplied from the outdoor unit and
controls the fan motor speed.
● Q901 is switched on and off according to the signal at fan PWM output pin
J
to control the voltage which
is smoothed by D902, L901 and C901 to drive the fan motor.
● The output voltage is divided by R919 and R920 and is input to divided voltage output pin
8
; the micro
computer controls the fan PWM output so the output voltage is set to the specified value. The chopper
frequency of the fan PWM output is 15.7kHz.
● In the Fan current detection circuit, 35V line current is detected by R906 and input to fan current detection
pin
9
. Microcomputer detects overcurrent comparing it with the current judgment value corresponding to
the fan rotation speed.
TELECON
(AX-3U)
C601
TEMPORARY SWITCH
SW1
5V
0V
R609
MICRO COMPUTER
MICRO COMPUTER
(AX-3U)
FAN PWM
OUTPUT
FAN PWM
FEEDBACK
R916
5V
5V
Q903
35V
ICP2
Q901
Q902
R911
R913
R914
R915
R917
R906
L901
R912D901
RED
YEL
BLU
CN3M PIN NO.
D902 C901 R919
R920
57
C932
0V 0V
0V
0V
0V
0V
0V
R931
R932
R930
D904
FAN CURRENT
DETECTION
I
J
M
8
9
5
4
3
2
1
C942
CN10
Indoor DC
Fan motor
3
31
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