PACD011001C2 Outline of Control
Function UM Combination “MA1R Series” Using R-407C 427
[Defrosting operation]
The defrosting operation provides the following control functions.
[Defrosting operation ending conditions]
When the following conditions are met, the defrosting operation ends.
However, when the compressor stops during a defrosting operation, if condition (Tb > 12.5°C) is not met at
the next compressor startup, the defrosting operation starts and a 10-minute counter is activated when the
software startup is completed.
Defrost out
20 sec delay
20 sec delay
∗1
∗7
PI control
PI control
PI control ∗3
SH control
PI control
52Hz+OFF
67Hz+OFF
30 sec
50 sec
LP protection control after
this point
2000pls
500(∗4)
Normal control
Normal control
According to ∗6
OFF
Hot start
2 min
Defrost
Defrost IN
Exhaust from accumulator
INV
SVP
Outdoor EV
Outdoor fan
Indoor fan
4-way valve
Indoor EV
(unit with
thermostat ON)
OR
OR
&
DSHi>30
Th6 – Te>10
LP<0.1MPa
1 minute or more after
completion of defrosting
operation
Elapsed time of 10 minutes
Step at which
preparation mode
is activated is set
as upper limit.
SH control
according to
∗2
Operate all indoor unit EV as follows : 1000 pls (50 sec) → 0 pls (10 sec) →4-way
valve switching →0 pls (15 sec ∗5)
Signal output during oil
return/defrosting operation
preparation
Defrost
preparation
flag
∗1
Accumulator discharge operation ending
conditions
∗2
SH control by outdoor unit EV
PI control activated when SHS = 10
(initial opening degree: 200 pls
In the case of an LP retry, the next PI
control is provided at SHS = 5.
When condition ∗1 is met, the next startup
condition is reset to SHS = 10.)
∗3
When returning to normal outdoor EV control,
the PI control is provided at that opening
degree.
∗4
Opening degree of indoor unit EV during
defrosting operation
• Initial value: 500
• Next indoor unit EV opening degree (200-
2000) is determined based on (Th6 – Te < 15)
appearing time in previous defrosting operation
0 minute → +100
Less than 3 minutes → +0
3 minutes or more → –100
∗5
0 pls maintained after elapsed time of 15
seconds until LP < 0.2 MPa
∗6
Opens receiver solenoid valve for 60 seconds at
1 minute after the preparation mode is
activated.
However, the valve is closed when Th6 – Te < 0.
∗7
CU-8MA1XPK 52Hz + ON
CU-10MA1XPK 71Hz + ON
CU-16, 20MA1XPK 52Hz + ON + ON
(V0807)
OR
When distribution pipe temperatures at all heat exchanger
outlets (during cooling operation) are as follows: Tb > 12.5°C
When defrosting operation is conducted for 10 minutes
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