Gree GMV-VQ680WM/C-X Service Manual page 348

Gree
Step 13: System leakage inspection
1) Check each welding joints. Firstly, observe whether the welding joints are smooth
and whether there are obvious welding holes and other abnormal conditions.
2) Then, charge the unit system with high-pressure nitrogen for leak inspection. If it is
only for ODU maintenance, and it can be confirmed that there is no abnormality in the IDU
system, only charge the ODU with high-pressure nitrogen for leak inspection. Note that it is
necessary to simultaneously charge nitrogen from the high and low pressure sides. It is
recommended to charge the nitrogen valve at the same time with nitrogen. The nitrogen
pressure should be greater than 20kgf. Use soapy water to check whether the unit system
leaks, and focus on checking the service joints.
3) Finally, charge the system with high-pressure nitrogen to keep the system pressure
at above 25kgf. Close the large and small unit valves and hold the pressure of the IDUs and
ODU for more than 12 hours. If the pressure does not change, start vacuuming. Otherwise,
repeat the aforementioned procedure until the leaking point is located.
When checking whether there is any change in the pressure of the system, it is necessary to
eliminate the temperature influence as the temperature changes by 1°C, and the pressure
changes by about 0.01 MPa. For example, when the temperature of nitrogen is 30°C, the pressure
is 2.5 MPa. After the pressure is held for more than 12 hours, the temperature becomes 25°C, the
unit passes the test if the pressure is above 2.43 MPa.
Step 14: Recharging refrigeration oil
The amount of refrigeration oil needs to be recharged is mainly determined by the total
GMV6 HR DC Inverter VRF Units Service Manual
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