Gree LSQWRF35VM/NaA-M, Service Manual

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Test Operation, Troubleshooting and Maintenance
4.5 Routine maintenance
4.5.1 Repairs to refrigerant leakage
When soapsuds often used to detect leakage of a refrigeration system is applied to possible leakage
points. If there are bubbles, leaks occur and need repairs by brazing. If soapsuds does not work, an
electronic leak detector is an alternative. Intake and exhaust pressures indicate refrigerant charge. If leaks
exist or parts are going to be replaced, leakage test must be taken. Refrigerant charges in two following
cases should be treated in different manners.
(1) Full leaks
A leak test for the system must be taken with high-pressure nitrogen (15~20 kg) or refrigerant. If
brazing is needed, gases in the system must be evacuated. The system must be treated with vacuum
pumping before refrigerant charges.
1) Connect evacuation pipes with refrigerant nozzles at low-pressure and high-pressure sides;
2) Vacuumize the system piping by a vacuum pump.
Procedures (one system as an example):
Step 1: Remove the high-pressure nitrogen that was used for the leak test.
Step 2: Fix pressure gauges to refrigerant nozzles of high-pressure and low-pressure valves (note:
vacuum pumping should be done with both valves in the meantime.). Either of two dials must register low
pressures since only its readings indicate vacuum.
Low-pressure gauge
High-pressure gauge
Manifold gauge
Hose
Hose
Vacuum pumping
Step 3: Turn on switches at low-pressure and high-pressure sides. Start a vacuum pump let it continues
for 0.5~1.0 hour after the reading of a pressure gauge falls to -1bar.
Step 4: Close the valves connected to the vacuum pump shown in the figure above and then shut down
the pump. (Notice: it must be done in this order, or gases will enter the system again.)
Step 5: Take a pressure test to make sure that the pressure of the system is no less than 80Pa and will
not noticeably rebound within 1 hour.
Up to now, vacuum pumping has been finished.
3) Keep the pressure for 30 minutes, and charge refrigerant when the pressure is no more than 100Pa.
Start charging according to the proper volume indicated by the nameplate and main technical parameters
table.