Indoor Fan Motor Control; Auto Vane Operation - Mitsubishi Electric MSH-18RV Service Manual

9-5. 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 feed
back the rotational frequency. Comparing the current rotational frequency with the target rotational frequency
(High, Med., Low), the microprocessor controls IC141(MSH-18/24RV)/ SR141(MSH-30RV) and 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) the fan motor is regarded locked-up. Then the electric current to the fan motor is shut
off. 3 minutes later, the electric current is applied to the fan motor again. During the fan motor lock-up, the OPERATION
INDICATOR Indicator lamp flashes on and off to show the fan motor abnormality. (Refer to page 55 or 56.)

9-6. 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 changes as follows by pressing the VANE CONTROL button(MSH-18/24RV)/
VANE button(MSH-30RV).
(3) Positioning
The vane is once pressed to the vane stopper below to confirm the standard position and then set to the desired angle.
Confirming of standard position is performed in case of follows.
(a) When the OPERATE/STOP (ON/OFF) button is pressed.
(b) When the vane control is changed from AUTO to MANUAL.
(c) When the SWING is finished.
(d) When the test run starts.
(e) When the power supply turns ON.
(4) VANE AUTO ( ) mode
In VANE AUTO mode, the microprocessor automatically determines the vane angle and operation to make the optimum
room-temperature distribution.
In COOL and DRY operation
In HEAT operation
Rotational frequency
High
1 2
AUTO
Horizontal
High
Med.
Low
time
3 4
Middle Downward
Vane angle is fixed to Angle 1.
Vane angle is fixed to Angle 4.
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5
Swing