Evacuation And Recharge (R-404A); Brazing - Hoshizaki KM-1800SWH/3 Service Manual

1) 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. Install the
new drier with the arrow on the drier in the direction of the refrigerant flow.
) Braze all fittings while purging with nitrogen gas flowing at a pressure of 3 to 4 PSIG.
Note: Because the pipes in the evaporator case are specially coated to resist corrosion,
it is important to make connections outside the evaporator case when possible. If
it is necessary to braze inside the evaporator case, use sandpaper to remove the
coating from the brazing connections before unbrazing the components.
3) Check for leaks using nitrogen gas (140 PSIG) and soap bubbles. Do not use R-404A
as a mixture with pressurized air for leak testing. Refrigerant leaks can be detected by
charging the unit with a trace of refrigerant, raising the pressure with nitrogen and using
an electronic leak detector.

3. Evacuation and Recharge (R-404A)

1) Attach a vacuum pump to the system. Be sure the charging hoses are connected to
both high and low-side service valves.
The vacuum level and vacuum pump may be the same as those for current
refrigerants. However, the rubber hose and gauge manifold to be used for
evacuation and refrigerant charge should be exclusively for POE oils.
) Turn on the vacuum pump. Never allow the oil in the vacuum pump to flow backward.
3) Allow the vacuum pump to pull down to a 9.9" Hg vacuum. Evacuating period depends
on pump capacity.
4) Close the low-side valve and high-side valve on the service manifold.
5) Disconnect the vacuum pump and attach a refrigerant service cylinder to the high-side
line. Remember to loosen the connection and purge the air from the hose.
For air-cooled and water-cooled models, see the nameplate for the required refrigerant
charge. For remote air-cooled models, see the rating label inside the icemaker.
Hoshizaki recommends only virgin refrigerant or reclaimed refrigerant which meets ARI
Standard No. 700-88 be used.
6) A liquid charge is recommended for charging an R-404A system. Invert the service
cylinder and place it on scales. Open the high-side, service manifold valve.
7) Allow the system to charge with liquid until the proper charge weight is met.
8) If necessary, add any remaining charge to the system through the low-side. Use a
throttling valve or liquid dispensing device to add the remaining liquid charge through
the low-side service valve with the unit running.
9) Close the two refrigerant service valves, and disconnect the service manifold hoses.
10) Cap the service valves to prevent a possible leak.
IMPORTANT
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