Hoshizaki 1800ALKE(-N), Service Manual

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138
5. 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) Disconnect the power source.
2) Remove the front panel.
3) Recover the refrigerant and store it in a proper container, if required by an applicable law
(See “1. [b] REFRIGERANT RECOVERY”).
4) Remove the expansion valve bulb at the evaporator outlet.
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 0.2 - 0.3 bar.
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 120°C.
7) Install the new drier (See "4. DRIER").
8) Check for leaks using nitrogen gas (10 bar) and soap bubbles.
9) Evacuate the system, and charge it with refrigerant. See the nameplate for the required
refrigerant charge (See "1. [c] EVACUATION AND RECHARGE").
10) Attach the bulb to the suction line. Be sure to secure the bulb using a wire or clamp and
replace the insulation.
11) Place the new set of expansion valve covers in position.
12) Refit the front panel in its correct position.
13) Connect the power source.