Evacuation And Recharge (R-404A) - Hoshizaki KM-1900SAH 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.
2) 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) 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.

3. Evacuation and Recharge (R-404A)

1) Attach a vacuum pump to the system. Be sure to connect the charging hoses to both
the 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 service manifold to be used for
evacuation and refrigerant charge should be exclusively for POE oils.
2) Turn on the vacuum pump. Open the service manifold valves. Never allow the oil in the
vacuum pump to flow backwards.
3) Allow the vacuum pump to pull down to a 29.9" Hg vacuum. Evacuating period depends
on pump capacity.
4) Close both the high and low-side valves on the service manifold.
5) Turn off the vacuum pump. Disconnect the vacuum pump hose and attach it to a
refrigerant service cylinder. 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 700 (latest edition) 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 valve on the service manifold.
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 refrigerant service valves and the service manifold valves, then disconnect
the service manifold hoses.
10) Cap the service valves to prevent a possible leak.
IMPORTANT
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