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E. Removal and Replacement of Expansion Valve
IMPORTANT
Sometimes moisture in the refrigeration circuit exceeds the drier capacity and
freezes up at the expansion valve. Always install a new drier every time the
sealed refrigeration system is opened. Do not replace the drier until after all
other repair or replacement has been made.
1) Turn off the power.
2) Remove the panels.
3) Recover the refrigerant and store it in an approved container.
4) Remove the insulation and the expansion valve bulb on the suction line.
5) Remove the expansion valve cover, and disconnect the expansion valve using brazing
equipment.
6) Braze the new expansion valve with nitrogen gas flowing at the pressure of 3 to 4 PSIG.
WARNING
Always protect the valve body by using a damp cloth to prevent the valve from
overheating. Do not braze with the valve body exceeding 250°F (121°C).
7) Install the new drier.
8) Check for leaks using nitrogen gas (140 PSIG) and soap bubbles.
9) Evacuate the system, and charge it with refrigerant. For air-cooled and water-cooled
models, see the nameplate for the required refrigerant charge. For remote air-cooled
models, see the charge label in the machine compartment.
10) Attach the expansion valve bulb to the suction line in the same location as the previous
bulb. The bulb should be at the 12 o'clock position on the tube. Be sure to secure the
bulb with the clamp and holder and to insulate it.
11) Place the expansion valve cover in position.
12) Replace the panels in their correct positions.
13) Turn on the power supply.
F. Removal and Replacement of Hot Gas Valve and Line Valve
IMPORTANT
1. Always use a copper tube of the same diameter and length when replacing
the hot gas lines; otherwise the performance may be reduced.
2. Always install a new drier every time the sealed refrigeration system is
opened. Do not replace the drier until after all other repair or replacement
has been made.
3. Always replace the strainer when replacing the hot gas valve.