Midea M2OC-18HFN1-M Service Manual page 18

Exit low ambient cooling
mode ,
38
for 1 minute
27
Low
off
7.4.3.2 Heating mode
For M3OD-27HRDN1-M:
For M2OC-18HFN1-M,M2OD-18HFN1-M,M3OC-
30HRFN1-M, M4OC-36HRFN1-M:
T4
E
21℃
19℃
D
18℃
16℃
C
15℃
13℃
B
12℃
10℃
A
7.4.4 Electronic Expansion Valve (EXV)
Control
1.EXV will be fully closed when turning on the
power. Then EXV will be standby with 350P open
and will open to target angle after compressor
starts.
2.EXV will close with -160P when compressor
stops. Then EXV will be standby with 350P open
run with high fan
30
23
DC_FAN_SSLOW_SPD_ADD
DC_FAN_SLOW_SPD_ADD
DC_FAN_MIN_SPD_ADD
DC_FAN_MID_SPD_ADD
DC_FAN_HI_SPD_ADD
and will open to target angle after compressor
starts.
3.The action priority of the EXVs is A-B-C-D.
4.Compressor and outdoor fan start operation
only after EXV is initialized.
7.4.4.1 Cooling mode
The initial open angle of EXV is 250P, adjustment
range is 100-350p. When the unit start to work for
3 minutes, the outdoor will receive indoor units( of
capacity demand) T2B information and calculate
the average of them. After comparing each
indoor's T2B with the average, the outdoor gives
the following modification commands:
If the T2B＞average, the relevant valve needs
more 16p open;
If the T2B= average, the relevant valve's open
range remains;
If the T2B＜average, the relevant valve needs
more 16p close.
This modification will be carried out every 2
minutes.
7.4.4.2 Heating mode
The initial open angle of EXV is 250P, adjustment
range is 100-350p.. When the unit start to work
for 3minutes, the outdoor will receive indoor
units( of capacity demand) T2 information and
calculate the average of them. After comparing
each indoor's T2 with the average, the outdoor
gives the following modification commands:
If the T2＞average+2, the relevant valve needs
more 16p close;
If average+2≥the T2≥ average-2, the relevant
valve's open range remains;
If the T2＜average-2, the relevant valve needs
more 16p open.
This modification will be carry out every 2 minutes.
7.4.5 Four-way valve control
In heating mode, four-way valve is opened. In
defrosting, four-way valve operates in according
to defrosting action. In other modes, four-way
valve is closed. When the heating mode to other
modes, the four-way valve is off after compressor
is off for 2 minutes. Failure or protection (not
including discharge temperature protection, high
and low pressure protection), four-way valve
immediately shuts down.