User's Manual

53
5. Removal and Replacement of Expansion Valve
IMPORTANT
Sometimes moisture in the refrigerant 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 supply.
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 a pressure of 3-4 PSIG.
WARNING
1. Do not heat the wall. Place a steel barrier for protection.
2. 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.
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 bulb to the suction line in position. Be sure to secure it with clamps and to insulate it.
11) Place the new set of expansion valve covers in position.
12) Replace the panels in their correct position.
13) Turn on the power supply.