Expansion Valve - Hoshizaki KMD-210AB-HC Service Manual

6. EXPANSION VALVE

The water in the refrigeration circuit may exceed the capacity of the drier and
freeze in 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) Remove the refrigerant from the unit and then any residual refrigerant still existing in the
unit to allow welding process. (See "2. WELDING REPAIR FOR R290 REFRIGERATION
CIRCUIT".)
4) Remove the insulation and the expansion valve bulb on the suction line.
5) Remove the expansion valve cover and disconnect the expansion valve. Place the new
expansion valve in position.
6) Remove the drier, then place the new drier in position.
7) Braze all fittings while purging with nitrogen gas flowing at a pressure of 20 to 30 kPa.
Always protect the valve body by using a damp cloth to prevent the valve from
overheating. Do not braze with the valve body exceeding 115°C.
8) Use an electronic leak detector or soap bubbles to check for leaks. Add a trace of
refrigerant to the system (if using an electronic leak detector), and then raise the
pressure using nitrogen gas (970 kPa). DO NOT use R290 as a mixture with pressurized
air for leak testing.
9) Evacuate the system, and charge it with refrigerant. For air-cooled and water-cooled
models, see the nameplate for the required refrigerant charge.
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.
IMPORTANT
WARNING
35