Mitsubishi Electric City Multi CMB-WP108V-G, Service Manual

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iii iii HWE1113B GB
Precautions for handling units for use with R410A
CAUTION
Do not use the existing refrigerant piping.
Œ
A large amount of chlorine that may be contained in the re-
sidual refrigerant and refrigerating machine oil in the exist-
ing piping may cause the refrigerating machine oil in the
new unit to deteriorate.
Œ
R410A is a high-pressure refrigerant and can cause the
existing pipes to burst.
Use refrigerant pipes made of phosphorus deoxidized
copper. Keep the inner and outer surfaces of the pipes
clean and free of such contaminants as sulfur, oxides,
dust, dirt, shaving particles, oil, and water.
These types of contaminants inside the refrigerant pipes
may cause the refrigerant oil to deteriorate.
Store the pipes to be installed indoors, and keep both
ends of the pipes sealed until immediately before braz-
ing. (Keep elbows and other joints wrapped in plastic.)
Infiltration of dust, dirt, or water into the refrigerant system
may cause the refrigerating machine oil to deteriorate or
cause the unit to malfunction.
Use a small amount of ester oil, ether oil, or alkylben-
zene to coat flares and flanges.
Infiltration of a large amount of mineral oil may cause the re-
frigerating machine oil to deteriorate.
Charge liquid refrigerant (as opposed to gaseous re-
frigerant) into the system.
If gaseous refrigerant is charged into the system, the com-
position of the refrigerant in the cylinder will change and
may result in performance loss.
Use a vacuum pump with a reverse-flow check valve.
If a vacuum pump that is not equipped with a reverse-flow
check valve is used, the vacuum pump oil may flow into the
refrigerant cycle and cause the refrigerating machine oil to
deteriorate.
Prepare tools for exclusive use with R410A. Do not use
the following tools if they have been used with the con-
ventional refrigerant (gauge manifold, charging hose,
gas leak detector, reverse-flow check valve, refrigerant
charge base, vacuum gauge, and refrigerant recovery
equipment.).
Œ
If the refrigerant or the refrigerating machine oil left on
these tools are mixed in with R410A, it may cause the re-
frigerating machine oil to deteriorate.
Œ
Infiltration of water may cause the refrigerating machine
oil to deteriorate.
Œ
Gas leak detectors for conventional refrigerants will not
detect an R410A leak because R410A is free of chlorine.
Do not use a charging cylinder.
If a charging cylinder is used, the composition of the refrig-
erant will change, and the unit may experience power loss.
Exercise special care when handling the tools for use
with R410A.
Infiltration of dust, dirt, or water into the refrigerant system
may cause the refrigerating machine oil to deteriorate.