Hoshizaki DCM-500BWH-OS, DCM-500BAH-OS service manual Removal and Replacement of Expansion Valve

C. 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)Move the control switch to the "OFF" position, then turn off the power supply. Remove the front and top panels, then move the power switch to the "OFF" position.

2)Remove the apron panel, then remove the left side panel.

3)Recover the refrigerant and store it in an approved container.

4)Disconnect the drip tray hose from the tee. Remove the four screws securing the drip tray, then remove the drip tray and hose.

5)Remove the insulation and the expansion valve bulb on the suction line.

6)Remove the expansion valve cover and disconnect the expansion valve.

7)Place the new expansion valve in position.

8)Remove the drier, then place the new drier in position.

9)Braze all fittings while purging with nitrogen gas flowing at a pressure of 3 to 4 PSIG.

CAUTION

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).

10)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 (140 PSIG). DO NOT use R-404A as a mixture with pressurized air for leak testing.

11)Evacuate the system, and charge it with refrigerant. See the nameplate for the required refrigerant charge.

12)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.

13)Place the expansion valve cover in position.

14)Replace the drip tray and drip tray hose in their correct positions. Secure the hose to the tee. Pour water into the drip tray and check for leaks.

15)Move the power switch to the "ON" position, then replace the panels in their correct positions.

16)Turn on the power supply, then move the control switch to the "ICE" position to start the automatic icemaking process.

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