Cautions For Service; Refrigerant Charge - Mitsubishi Electric PUZ-WM50VHA Service Manual

[1] Warning for service
(1) Do not alter the unit.
(2) For installation and relocation work, follow the instructions in the Installation Manual and use tools and pipe
components specifically made for use with refrigerant specified in the outdoor unit installation manual.
(3) Ask a dealer or an authorized technician to install, relocate and repair the unit.
For appliances not accessible to the general public.
(4) Refrigerant pipes connection shall be accessible for maintenance purposes.
(5) If the heat pump unit is installed in a small room or closed room, measures must be taken to prevent the refrigerant
concentration in the room from exceeding the safety limit in the event of refrigerant leakage. Should the refrigerant
leak and cause the concentration limit to be exceeded, hazards due to lack of oxygen in the room may result.
(6) Keep gas-burning appliances, electric heaters, and other fire sources (ignition sources) away from the location
where installation, repair, and other work will be performed.
If refrigerant comes into contact with a flame, poisonous gases will be released.
(7) When installing or relocating, or servicing the heat pump unit, use only the specified refrigerant (R32) to charge
the refrigerant lines.
Do not mix it with any other refrigerant and do not allow air to remain in the lines.
If air is mixed with the refrigerant, then it can be the cause of abnormal high pressure in the refrigerant line, and
may result in an explosion and other hazards.
(8) After installation has been completed, check for refrigerant leaks. If refrigerant leaks into the room and comes
into contact with the flame of a heater or portable cooking range, poisonous gases will be released.
(9) Do not use low temperature solder alloy in case of brazing the refrigerant pipes.
(10) When performing brazing work, be sure to ventilate the room sufficiently or work outside. Make sure that there
are no hazardous or flammable materials nearby.
When performing the work in a closed room, small room, or similar location, make sure that there are no refriger-
ant leaks before performing the work.
If refrigerant leaks and accumulates, it may ignite or poisonous gases may be released.
(11) Do not install the unit in places where refrigerant may build-up or places with poor ventilation such as a semi-base-
ment: Refrigerant is heavier than air, and inclined to fall away from the leak source.
(12) The appliance shall be stored in a room without continuously operating ignition sources (for example: open
flames, an operating gas appliance or an operating electric heater).
(13) Do not pierce or burn.
(14) Do not use means to accelerate the defrosting process or to clean, other than those recommended by the manu-
facturer.
(15) Be aware that refrigerants may not contain an odour.
(16) Pipe-work shall be protected from physical damage.
(17) Compliance with national gas regulations shall be observed.
(18) Keep any required ventilation openings clear of obstruction.
(19) Servicing shall be performed only as recommended by the manufacturer.
(20) The appliance shall be stored in a well-ventilated area where the room size corresponds to the room area as
specified for operation.
(21) Maintenance, service and repair operations shall be performed by authorized technician with required qualification.
(22) Be sure to have appropriate ventilation in order to prevent ignition. Furthermore, be sure to carry out fire preven-
tion measures that there are no dangerous or flammable objects in the surrounding area.

[2] Cautions for service

(1) Perform service after recovering the refrigerant left in unit completely.
(2) Do not release refrigerant in the air.
(3) After completing service, charge the cycle with specified amount of refrigerant.
(4) When performing service, install a filter drier simultaneously.
Be sure to use a filter drier for new refrigerant.

[3] Refrigerant charge

When charging directly from cylinder
R32 is a single refrigerant and its composition does not change. Therefore, both liquid charging and gas charging are
possible. Liquid charging of refrigerant all at once from the low pressure side may cause the compressor malfunction.
Accordingly, make sure that charging is gradual.
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Liquid
Charging liquid refrigerant
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