Kaisai 06RY1, Service Manual

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M thermal Mono
20 202008
Midea
M
ther
ma
l Mo
no
Se
rvice M
an
ual
4.4 Four-way Valve Control
The four-way valve is used to change the direction of refrigerant flow through the water side heat exchanger in order to
switch between cooling and heating/DHW operations.
During heating and DHW operations, the four-way valve is on; during cooling and defrosting operations, the four-way
valve is off.
4.5 Electronic Expansion Valve Control
The position of the electronic expansion valve (EXV) is controlled in steps from 0 (fully closed) to 480 (fully open).

At power-on:

The EXV first closes fully, then moves to the standby position. After a few seconds the EXV moves to an initial
running position, which is determined according to operating mode and outdoor ambient temperature. After a
further a few minutes, the EXV is controlled according to suction superheat and discharge temperature. Once a
further a few minutes have elapsed, the EXV is then controlled according to suction superheat, discharge
temperature and compressor speed.

When the outdoor unit is in standby:

The EXV is at standby position.

When the outdoor unit stops:

The EXV first closes fully, then moves to the standby position.
4.6 Outdoor Fan Control
The speed of the outdoor unit fan(s) is adjusted in steps, as shown in Table 3-4.3.
Table 3-4.3: Outdoor fan speed steps
Fan speed index
Fan speed (rpm)
6kW 8-10kW 12-14kW 16kW
0 0 0 0 0
1 200 200 200 200
2 250 250 250 250
3 300 300 300 300
4 350 350 350 350
5 400 400 400 400
6 450 450 450 450
7 500 500 500 500
8 530 530 550 550
9 550 550 580 600
10 580 580 610 650
11 600 600 630 700
12 600 600 650 730
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M thermal Mono
202008 21
Part
3
- Con
trol
4.7 Spray liquid cooling control
When the discharge temperature of compressor exceeds 105
℃
, the solenoid valve opens and the frequency of
compressor drops in order to reduce the discharge temperature. When the discharge temperature is below 100
℃
, the
solenoid valve closes.
If the discharge temperature exceeds 108
℃
while the spray liquid cooling control is in progress, which is judged every 20s,
the frequency of compressor drops 4Hz until the minimum frequency which differs from every model. When the discharge
temperature is below 101
℃
, the compressor runs at the current frequency.
5 Protection Control
5.1 High Pressure Protection Control
This control protects the refrigerant system from abnormally high pressure and protects the compressor from transient
spikes in pressure.
Figure 3-5.1: High pressure protection control
Notes:
1. P
c
: Discharge pressure
When the discharge pressure rises above 4.3MPa the system displays P1 protection and the unit stops running. When the
discharge pressure drops below 3.6MPa, the compressor enters re-start control.
5.2 Low Pressure Protection Control
This control protects the refrigerant system from abnormally low pressure and protects the compressor from transient
drops in pressure.
Figure 3-5.2: Low pressure protection control
Notes:
1. P
e
: Suction pressure
When the suction pressure drops below 0.14MPa the system displays P0 protection and the unit stops running. When the
suction pressure rises above 0.3MPa, the compressor enters re-start control.
P
c
> 4.3MPa P
c
< 3.6MPa
Normal operation
High pressure protection, error code P1 is displayed
P
e
< 0.14MPa P
e
> 0.30MPa
Normal operation
Low pressure protection, error code P0 is displayed
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