Toshiba MMU-AP0152SH, Service Manual

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• New Refrigerant (R410A)
This air conditioner adopts a new HFC type refrigerant (R410A) which does not deplete the ozone layer.
1. Safety Caution Concerned to New Refrigerant
The pressure of R410A is high 1.6 times of that of the former refrigerant (R22). Accompanied with change of
refrigerant, the refrigerating oil has been also changed. Therefore, be sure that water, dust, the former refriger-
ant or the former refrigerating oil is not mixed into the refrigerating cycle of the air conditioner with new refriger-
ant during installation work or service work. If an incorrect work or incorrect service is performed, there is a
possibility to cause a serious accident. Use the tools and materials exclusive to R410A to purpose a safe work.
2. Cautions on Installation/Service
(1) Do not mix the other refrigerant or refrigerating oil.
For the tools exclusive to R410A, shapes of all the joints including the service port differ from those of the
former refrigerant in order to prevent mixture of them.
(2) As the use pressure of the new refrigerant is high, use material thickness of the pipe and tools which are
specified for R410A.
(3) In the installation time, use clean pipe materials and work with great attention so that water and others do
not mix in because pipes are affected by impurities such as water, oxide scales, oil, etc. Use the clean
pipes.
Be sure to brazing with flowing nitrogen gas. (Never use gas other than nitrogen gas.)
(4) For the earth protection, use a vacuum pump for air purge.
(5) R410A refrigerant is azeotropic mixture type refrigerant. Therefore use liquid type to charge the refrigerant.
(If using gas for charging, composition of the refrigerant changes and then characteristics of the air condi-
tioner change.)
3. Pipe Materials
For the refrigerant pipes, copper pipe and joints are mainly used. It is necessary to select the most appropriate
pipes to conform to the standard. Use clean material in which impurities adhere inside of pipe or joint to a
minimum.
(1) Copper pipe
<Piping>
The pipe thickness, flare finishing size, flare nut and others differ according to a refrigerant type.
When using a long copper pipe for R410A, it is recommended to select “Copper or copper-base pipe without
seam” and one with bonded oil amount 40mg/10m or less. Also do not use crushed, deformed, discolored
(especially inside) pipes. (Impurities cause clogging of expansion valves and capillary tubes.)
<Flare nut>
Use the flare nuts which are attached to the air conditioner unit.
(2) Joint
The flare joint and socket joint are used for joints of the copper pipe.
The joints are rarely used for installation of the air conditioner. However clear impurities when using them.