![Mitsubishi Electric MSC-CA20VB Service Technical Manual Download Page 77](http://html.mh-extra.com/html/mitsubishi-electric/msc-ca20vb/msc-ca20vb_service-technical-manual_1810424077.webp)
77
High
Med.
Low
Super High
Super High
time
Rotational frequency
6-5. INDOOR FAN MOTOR CONTROL
(1) Rotational frequency feedback control
The indoor fan motor is equipped with a rotational frequency sensor, and outputs signal to the microprocessor to feedback
the rotational frequency. Comparing the current rotational frequency with the target rotational frequency (Super High, High,
Med., Low), the microprocessor adjusts fan motor electric current to make the current rotational frequency close to the
target rotational frequency. With this control, when the fan speed is switched, the rotational frequency changes smoothly.
(2) Fan motor lock-up protection
When the rotational frequency feedback signal has not output for 12 seconds, (or when the microprocessor cannot
detect the signal for 12 seconds) energizing to the fan motor is stopped. Then the microprocessor retries detection 3
times every 30 seconds. If the microprocessor still cannot detect the signal, the fan motor is regarded locked-up. When
the fan motor lock-up, POWER lamp flashes on and off to show the fan motor abnormality.
6-6. OUTDOOR FAN MOTOR CONTROL
MUZ-GA35
Fan speed is switched according to the compressor frequency.
COOL
Fan speed
Up
Down
Up
Down
Mode
HEAT
Compressor frequency
MUZ-GA35
<Relation between compressor frequency and fan speed>
54Hz
41Hz
54Hz
41Hz
Up
Down
Fan speed
High
Low
Compressor frequency
Min.
Max.
(3) Positioning
The vane presses the vane stopper once to confirm the standard position and then moves to the set angle.
Confirming of standard position is performed in case of follows.
(a) When the operation starts or finishes (including timer operation).
(b) When the test run starts.
(c) When multi-standby starts or finishes.
6-7. AUTO VANE OPERATION
1. Horizontal vane
(1) Vane motor drive
These models are equipped with a stepping motor for the horizontal vane. The rotating direction, speed, and angle of
the motor are controlled by pulse signals (approx. 12V) transmitted from indoor microprocessor.
(2) The horizontal vane angle and mode change as follows by pressing VANE CONTROL button.
OBT06D--3qxp 07.3.2 9:42 AM Page 77