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5. Removal and Replacement of Thermostatic 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, and unplug the dispenser.
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. See the nameplate for the required
refrigerant charge.
10) Place the expansion valve in position.
11) Place the new set of expansion valve covers in position.
12) Attach the expansion valve bulb to the low-side line, and secure it with bulb holder and
clamps.
13) Cover the expansion valve bulb tightly with the insulation.