Refrigeration Circuit Service Information - Hoshizaki KM-420MWJ Service Manual

B. Refrigeration Circuit Service Information
MRJZ models with URC-5FZ
• Repairs requiring the refrigeration circuit to be opened must be performed by
properly trained and EPA-certified service personnel.
• 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.
• Always recover the refrigerant and store it in an approved container. Do not
discharge the refrigerant into the atmosphere.
• Do not leave the system open for longer than 15 min. when replacing or servicing
parts. The Polyol Ester (POE) oils used in R-404A applications can absorb
moisture quickly. Therefore it is important to prevent moisture from entering the
system when replacing or servicing parts.
• 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.
• When brazing, protect the drier by using a wet cloth to prevent the drier from
overheating. Do not allow the drier to exceed 250°F (121°C).
1. Refrigerant Recovery
The condensing unit and icemaker are provided with refrigerant shutoff valves. Using
proper refrigerant practices, recover the refrigerant. Recovery via the condensing unit's
refrigerant shutoff valves is recommended. Store the refrigerant in an approved container.
Do not discharge the refrigerant into the atmosphere.
2. Brazing
• R-404A itself is not flammable at atmospheric pressure and temperatures up to
176°F (80°C).
• R-404A itself is not explosive or poisonous. However, when exposed to high
temperatures (open flames), R-404A can be decomposed to form hydrofluoric
acid and carbonyl fluoride both of which are hazardous.
• Do not use silver alloy or copper alloy containing arsenic.
1) 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.
WARNING
NOTICE
WARNING
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