Daikin VRV RSXYP16KJY1, Руководство по обслуживанию

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Method of Troubleshooting Si30-408
72 Troubleshooting
3. Method of Troubleshooting
3.1 Excessive / Insufficient Charging of Refrigerant
For VRV system, troubleshooting can be executed only with the operating conditions of air
conditioner relating to pressure control and electronic expansion valve control, and the methods
of judgment are shown below.
1. For excessive charging
(The operating capacity of compressor has a tendency to increase in cooling while decrease
in heating.)
1. Operate with light load by using capacity control of compressor due to increasing of high
pressure (condensing temperature).
(Compressor capacity cannot be controlled to obtain the target pressure.)
As a result, circulation volume of refrigerant decreases, and cooling and heating will
malfunction.
2. In heating operation, since a large amount of liquid refrigerant is stagnant between the
outlet of condenser and the liquid line, the cooling temperature of refrigerant become
large and discharge air temperature lowers even when the target pressure (see below) is
maintained in heating operation. Moreover, the detecting temperature of liquid pipe
thermistor in indoor unit may be kept at approx. 40°C or higher normally, while in this
case, the temperature may lower to approx. 35°C or lower due to a stagnancy of
refrigerant. Accordingly, the discharge temperature may become approx. 30°C.
3. In heating operation, the control is executed during closing operation of EV opening
degree.
Since the liquid pressure rises with the rising high pressure, even if the EV is throttled to
the minimum opening degree (200 pls), refrigerant cannot be super heated at the outlet
of heat exchanger and liquid refrigerant which does not evaporate returns to compressor,
resulting an operation so called "wet operation".
• Superheated degree = 0
→
The discharge pipe temperature lowers.
(Condensing tempe 20°C or less)
2. For insufficient charging
(The operating capacity of compressor has a tendency to decrease in cooling while increase
in heating.)
1. The discharge pipe temperature of compressor rises. (Suction SH increases, and
discharge pipe temperature also increases.)
2. Refrigerant at the outlet of evaporator is superheated. (Electronic expansion valve will be
opened fully.)
In this case, for the suction superheat degree of compressor is increased, alarm display
of insufficient gas (U0) is displayed.
3. In cooling operation, when the operation capacity of compressor is small, since the low
pressure (evaporating pressure) is low against refrigerant load, the unit cannot be
operated with required capacity due to decreasing of refrigerant circulation volume. In
heating operation, it is required to check that the difference between high pressure and
liquid pressure is 0.3 to 0.4 MPa.
Due to the characteristic of expansion valve, refrigerant cannot flow easily when the
pressure difference between inlet and outlet of the valve is 0.2 MPa or more, therefore,
liquid refrigerant will be stagnant between indoor heat exchanger and liquid piping.
Large pressure difference
→ → → →
Shortage of refrigerant
Small pressure difference
→ → → →
Excessive charge of refrigerant
Target Pressure and Temperature
* Above target temperature stands for the saturation temperature at gas side.
Target condensing temperature /
High pressure
Target evaporating temperature /
Low pressure
R22 46
°C
1.8MPa 5.5
°C
0.59MPa
R407C 48
°C
1.9MPa 7.5
°C
0.58MPa
R410A 46
°C
2.8MPa 6.0
°C
0.96MPa