Control And Functions - Midea M2OC-18HFN1-M Service Manual

1.If the compressor frequency keeps lower than
RET_OIL_FREQ1_ADD for
RET_OIL_TIME1_ADD,the AC will rise the
frequency to RET_OIL_FREQ2_ADD for
RET_OIL_TIME2_ADD and then resume to
former frequency.
2.During the oil return process, the EXV will keep
300p while the indoor units will keep the current
running mode.
7.3.11 Compressor preheating functions
----Preheating permitting condition:
If T4(outdoor ambient temperature)＜3℃ and
newly powered on or if T4＜3℃ and compressor
has stopped for over 3 hours, the compressor
heating cable will work.
----Preheating mode:
A weak current flow through the coil of
compressor from the wiring terminal of
compressor, then the compressor is heated
without operation.
----Preheating release condition:
If T4＞5℃ or the capacity demand isn't zero,
preheating function will stop.
7.3.12 Compressor crankcase heater
----Preheating permitting condition:
① When T4<3 ℃ within 5 seconds of being
plugged in, the crankcase heater will be
active.
② When T4<3 ℃ and the compressor is not
running for 3 hours, the crankcase heater will
be active.
----Preheating release condition:
When T4≧5℃ or the indoor has capacity
demand, the crankcase heater will stop work.

7.4 Control and Functions

7.4.1 Capacity Request Calculation
Total capacity Request=Σ(Norm code × HP) /10×
modify rate+ correction
Cooling mode:
T1 Ts
a
3
b
c
2
1 d
0
e
1
f
Capacity area
Norm code (N)
Model 9K
HP 1.0
Note: The final result is integer.
Plus all the indoor capacity request together, then
modify it by T4
When there's only one indoor unit
Outdoor temperature (T4)
Cooling
＞29℃
Modify rate 100%
When there're more than one indoor unit
Outdoor temperature (T4)
Cooling
＞25℃
Modify rate 100%
Note: The final result is integer.
In low ambient cooling mode, modify rate is fixed
as 40%.
According to the final capacity request to
confirm the operating frequency, as following
table.
COO
Frequency (Hz) 0
L_F1
Amendatory
capacity 0 1
demand.
4
3
2
1
0
a b c d e
3 2 1.5 1 0.5
12K 18K
1.2 1.5
18℃ ~ 29℃ <17℃
60% 40%
17℃ ~ 25℃ <17℃
80% 40%
...
COO COOL
...
L_F2 _F15
...
2 15
...
f
0
COO
L_F1
6
16