Mitsubishi Electric PLFY Series Technical & Service Manual page 24

9-1-2. Flow control valve
1) Summary of flow control valve (FCV) operation
The FCV is operated by a stepping motor, which operates by receiving a pulse signal from the indoor control board.
The FCV position changes in response to the pulse signal.
Indoor control board and FCV connection
Limit signal
(Opening
"0" signal)
Ø1
M
Ø3
Ø2 Ø4
Pulse signal output and valve operation
Output (phase)
number
Ø
1
Ø
2
Ø
3
Ø
4
2) FCV operation
(f)
TCH124A
Flow control valve
Connector
1
2
3
4
5
6
7
8
Output status
1 2 3
OFF ON ON
ON ON OFF
ON OFF OFF
OFF OFF ON
(a)
(b)
(c)
(e)
Control board
Gray
8
White GND
7
Purple 6
Blue 5
Ø4
Green
4
Ø3
Red
3
Ø2
Orange
2
Ø1
Yellow
1
Connector (CN8A)
The output pulse changes in the following order:
When the valve closes 1 → 2 → 3 → 4 → 1
4
When the valve opens 4 → 3 → 2 → 1 → 4
OFF
OFF
ON
ON
(a) Close
(b) Open
(c) Fully open valve (85 pulses)
(d) Fully close valve (770 pulses)
(e) No. of pulses
(f) Valve opening degree
(d)
24
Microprocessor
12V
Drive circuit
Ø4
Ø3
Ø2
Ø1