Operational Frequency Control Of Outdoor Unit; Outline - Mitsubishi Electric Mr.Slim MSZ09UN Service Manual

8-10. Operational frequency control of outdoor unit

1. Outline

The operational frequency is as following:
First, the target operational frequency is set based on the difference between the room temperature and the set temper-
ature.
Second, the target operational frequency is regulated by discharge temperature protection, high pressure protection,
electric current protection and overload protection and also by the maximum/minimum frequency.
Maximum/minimum frequency in each operation mode.
Applied
model
MSZ09UN
MSZ12UN
w The maximum frequency in COOL mode varies according to operation hours as shown below.
w However, it is under rating frequency when indoor fan speed is set to MANUAL Low or AUTO Low.
Maximum
frequency
Frequency
1Hr
2. Control by the difference between the room temperature and the set temperature
The frequency is controlled by the difference between the room temperature and the set temperature.
(1) Frequency when the unit starts operation
At the cooling operation
The difference between
the room temperature and
the set temperature (deg.)
1.8 or less
1.8 to 2.3
2.3 to 3.6
3.6 to 4.9
4.9 to 5.9
5.9 to 6.7
6.7 or more
(2) Frequency after the unit starts operation (Except for the case where the unit operates with the maximum operation
frequency)
In case the difference between the room temperature and the set temperature shown on (1) is changed during
operation or it is not changed for 128 seconds, the compressor operates with new operation frequency that is
calculated from actual operation frequency and the rate of change by fuzzy control.
COOL
rated
minimum
frequency
frequency
64
15
15 70
Rating or under rating frequency
Time: T
Operation frequency
(Hz)
15
15
20
25
30
40
MSZ09UN:80/ MSZ12UN:85
minimum
maximum
frequency
frequency
15
80
15
85
At the heating operation
The difference between
the room temperature and
the set temperature (deg.)
2.3 or less
2.3 to 3.1
3.1 to 4.1
4.1 to 5.4
5.4 to 5.9
5.9 to 6.7
6.7 or more
35
HEAT
rated maximum
frequency frequency
76 98
99 125
Operation frequency
(Hz)
15
15
20
25
30
40
MSZ09UN:98/ MSZ12UN:125
DRY
30
30