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

Page: 116 / 301

[
VII
Control ]
- 107 - HWE1113B GB
4-way valve control
-2- 4-way valve control
4-way valves (21S4M (a, b)) turn on or off according to the operation mode.
For 21S4Ma, ON indicates switching to the cooling side and OFF indicates switching to the heating side. For 21S4Mb, ON
indicates switching to the heating side and OFF indicates switching to the cooling side. For 21S4Ma, ON indicates switching
to the cooling side and OFF indicates switching to the heating side. For 21S4Mb, ON indicates switching to the heating side
and OFF indicates switching to the cooling side. When energized: ON; When de-energized: OFF
1) Select the installation site carefully, as some noise may be produced when the 4-way valve is switched.
Install the unit in a place where the noise from the unit will not be problem.
(Install the indoor units and HBC controller at least 5m [16-6/16ft] away from each other when installing in a space with low
background noise, e.g., hotel rooms.)
Install the unit in the ceiling of an area that are not always occupied by people, e.g., hallway, office kitchen, restrooms. (Do
not install the unit in the middle of a room.)
2) The elapsed time is used to reduce the switching frequency of the control modes between No. 1 or No. 6 AND No. 3 or No. 4.
3) Capacity control is determined depending on the opening of 2-way valve (FCV3) that adjusts the water flow rate.
No. Operation mode
4-way valve control
mode
4-way valve
21S4Ma 21S4Mb
1 Cooling-only Cooling ON OFF
2 Cooling (Half HEX) OFF OFF
3 Cooling-main Cooling-main OFF OFF
4 Heating-main Heating-main OFF OFF
5 Heating-only Warm heating OFF OFF
6 Heating OFF ON
7 Defrost Defrost The status before defrosting
maintained The status before defrosting
maintained
8 Stopped Stopped OFF OFF
Operation mode change
(Mixture of units in cooling and heating
→ Cooling-only/Heating-only)
Mixture of units in cooling and
heating(No.3 or 4)
(21S4Ma: OFF, 21S4Mb: OFF)
Operation mode
change
Cooling-only
Switches to the mild-cooling control (No. 2).
(21S4Ma: OFF, 21S4Mb: OFF)
The elapsed time since
the control mode is changed
≥ 30 minutes
Switches to the cooling control (No. 1).
(21S4Ma: ON, 21S4Mb: OFF)
No
* Note 3
* Note 2
No
Yes
Yes
Heating-only
Switches to the mild-heating control (No. 5).
(21S4Ma: OFF, 21S4Mb: OFF)
Switches to the heating control (No. 6).
(21S4Ma: OFF, 21S4Mb: ON)
No
* Note 3
* Note 2
No
Yes
Yes
The opening of 2-way valve
(FCV3) is too large.
The elapsed time since
the control mode is changed
≥ 30 minutes
The opening of 2-way valve
(FCV3) is too large.