Mitsubishi Electric City Multi CMB-WP108V-G, Service Manual

Page: 246 / 301

[
IX
Troubleshooting ]
- 237 - HWE1113B GB
[7] Servicing the HBC controller
3-way valve
1. 3-way valve, Refrigerant flow adjust valve
MV1 and MV2 (3-way valves) and FCV (water flow rate control valve) are driven by the pulse signal from the HBC controller
control board and are controlled by a stepping motor.
1) HBC controller control board and 3-way valves (MV1, MV2)
2) HBC controller control board and water flow rate control valve (FCV)
3) Pulse signal output and valve motion
Œ
If the LEDs (MV1a - MV1h, MV2a - MV2h, FCV3a - FCV3h) on the control board are lit, check the relevant three-way valves and
the refrigerant flow control valves for loose connectors and faulty wiring. Make sure that the valves are properly controlling the
refrigerant flow.
Œ
If the LED is unlit, check all three-way valves and refrigerant flow adjust valves for proper operation.
Œ
If the problem persists after taking the above measures, replace the circuit board.
Output (phase)
number
Output status
1 2 3 4
4 ON ON OFF OFF When valve opens (1600
ĺ
0): 4
ĺ
3
ĺ
2
ĺ
1
5 OFF ON ON OFF When valve closes (0
ĺ
1600): 1
ĺ
2
ĺ
3
ĺ
4
7 OFF OFF ON ON
8 ON OFF OFF ON
1
2
3
4
5
7
8
6
6
6
5
8
4
7
G ND
LED Mi c ro c omputer
12V
1
2
3
Limit signal
( O pening
"0" signal)
Cir c uit board
12V
4
5
6
7
8
1
2
3
M
4
5
6
6
5
8
4
7
G ND
LED
1
2
3
12V
3
2
1
3
2
1
12V
4
6
5
8
7
1
2
3
M Mi c ro c omputer
Limit signal
( O pening
"0" signal)
Cir c uit board