Servicing The Hbc Controller - Mitsubishi Electric CMB-WM108V-AA Service Handbook

[ VIII Troubleshooting ]

[6] Servicing the HBC controller

3-way valve
1. Valve block
VB3 (valve block) is driven by the pulse signal from the HBC controller control board and are controlled by a stepping motor.
1) HBC controller control board and valve block (VB3)
4
Limit signal
(Opening
"0" signal)
2) Pulse signal output and valve motion
Output (phase)
number
4
5
7
8
If the LEDs (VB3a-VB3p) on the control board are lit, check the relevant valve blocks for loose connectors and faulty wiring.
Make sure that the valve blocks are properly controlling the refrigerant flow.
If the LED is unlit, check all valve blocks for proper operation.
If the problem persists after taking the above measures, replace the circuit board.
HWE1708A
5
5
6
M
6
8
6
8
7
7
3 3
2
2
1
Output status
1 2
ON ON
OFF ON
OFF OFF
ON OFF
5
4
3
2
4
1
3
2
1
1
3 4
OFF OFF When valve opens (0→C800 or H800): 4→3→2→1
ON OFF When valve closes (C800 or H800→0): 1→2→3→4
ON ON
OFF ON
- 200 -
Circuit board
LED Microcomputer
GND
12V
12V
GB