LG DH65EL Service Manual - Page 18

3.4 HOW TO REPLACE THE REFRIGERATION SYSTEM 1. When replacing a refrigeration component, be sure to discharge the refrigerant system by using a refrigerant recovery system. 2. After discharging the unit completely, remove the desired component, and unbraze the pinch-off tubes. 3. Solder service valves into the pinch-off tube ports, leaving the valves open. 4. Solder the pinch-off tubes with service valves. 5. After doing the above procedures, the valve must be closed and left in place on the system for any subsequent procedures. 6. Evacuate as follows. 1) Connect the vacuum pump, as illustrated in Figure 31A. 2) Start the vacuum pump, slowly open manifold valves A and B two full turns counterclockwise and leave the valves open. The vacuum pump is now pulling through valves A and B to valve C by means of the manifold and entire system. CAUTION If high vacuum equipment is used, just crack valves A and B for a few minutes, then open slowly with the two full turns counterclockwise. This will keep oil from foaming and being drawn into the vacuum pump. 3) Operate the vacuum pump for 20 to 30 minutes, until 600 microns of vacuum are obtained. Close valves A and B, and observe vacuum gauge for a few minutes. A rise in pressure would indicate a possible leak or moisture remaining in the system. With valves A and B closed, stop the vacuum pump. 4) Remove the hose from the vacuum pump and place it on the charging cylinder. See Figure 31B. Open valve C. Discharge the line at the manifold connection. 5) The system is now ready for final charging. 7. Recharge as follows : 1) Refrigeration cycle systems are charged from the High-side. If the total charge cannot be put in the High-side, the balance will be put in the suction line through the access valve which you installed as the system was opened. 2) Connect the charging cylinder as shown in Figure 31B. With valve C open, discharge the hose at the manifold connection. 3) Open valve A and allow the proper charge to enter the system. Valve B is still closed. 4) If more charge is required, the high-side will not take it. Close valve A. 5) With the unit running, open valve B and add the balance of the charge. a. Do not add the liquid refrigerant to the Low- side. b. Watch the Low-side gauge; allow pressure to rise to 30 lbs. c. Turn off valve B and allow pressure to drop. d. Repeat steps B and C until the balance of the charge is in the system. 6) When satisfied the unit is operating correctly, use the pinch-off tool with the unit still running and clamp on to the pinch-off tube. Using a tube cutter, cut the pinch-off tube about 2 inches from the pinch-off tool. Use sil-fos solder and solder pinch-off tube closed. Turn off the unit, allow it to set for a while, and then test the leakage of the pinch-off connection. NOTE: REFRIGERANT R134a IS USED IN SOME MODELS. CHECK THE SPECIFICATION LABEL ON THE CABINET. When discharging refrigerant R134a, purging instrument should be used only for R134a, without mixing that of refrigerant R22. When checking the leakage of refrigerant R134a, leakage test tool should be used only for R134a. The pump for discharging should be high efficiency. Final discharging value must be managed below 0.5 Torr. Maximum water should be less than 150mg in the cycleall tubes and H/E assembly-system. If water quantity is over 150mg, it causes acid or corrosion in the cycle system and the capillary tube to be clogged by water and harmful materials. Models charged with refrigerant R134a should be used dryer to prevent water from overflowing. -18-