R.v. Coil Control; Indoor Fan Motor Control; Output Side; Input Side - Mitsubishi Electric MSZ-G09SV Service Manual

Compressor
Outdoor fan

9-12. R.V. coil control

Heating . . . . . . . . . . . . . . . . ON
Cooling . . . . . . . . . . . . . . . . OFF
Dry . . . . . . . . . . . . . . . . . . . OFF
NOTE: The 4-way valve reverses for 5 seconds right before start-up of the compressor.
Compressor
R.V.coil
Outdoor fan

9-13. Indoor fan motor control

The detected rotational frequency of the indoor fan motor (AC fan motor) is feed-back to the microprocessor and then
the microprocessor works to keep the rotational frequency at a fixed value against load fluctuation.
(1) Circuit block diagram
Microprocessor
(2) Control system
<Output side>
The microprocessor outputs pulse
every 100Hz (every 50Hz in half wave).
(Fan speed varies according to the
time span between a Zero-cross point
on the commercial wave and a pulse
output point.)
<Input side>
The microprocessor detects rotational
frequency of AC fan motor, using Hall
element in AC fan motor.
5 sec.
ON
OFF
ON
OFF
<COOL>
5 seconds
ON
OFF
ON
OFF
ON
OFF
every 100Hz pulse output
Rotational frequency
Electronic control P.C. board
The microproces-
sor drives solid
state relay on
Electronic control
P.C. board.
The microprocessor adjusts rotational frequen-
cy.
If feed-back pulses are not detected for 12
seconds, it is detected as abnormality of AC
fan motor, and indoor OPERATION INDICA-
TOR lamp flashes to show abnormality.
15 sec.
<HEAT>
5 seconds
AC motor
actuator
(Solid state relay)
Controlled voltage
is applied to AC
fan motor.
47
Solid state
relay output
AC fan
motor
230V AC
Rotational
frequency
sensor
part
output
input