Gree GWC09AA, Installation And Service Manual

Page: 97 / 136

GREE Service Manual GWC09AA / K5NNA6A Page 97
Refrigerant Circuit Evacuation
The Gree HC Air-Conditioner, as previously explained, is an intrinsic safe
system, which comes factory pre-assembled and already charged with R-290
refrigerant ready for installation and commissioning at the client’s site. The con-
tent of impurities, non-condensable gases (e.g. air, nitrogen, etc.) and humidity
within the refrigerant circuit is better than the industrial standard and this means
that the inner environment of the system is absolutely clean! For first field instal-
lation of the new air–conditioning system the use of a vacuum pump is not nec-
essary.
For After-Sales servicing procedures the diagram on the previous page indi-
cates the arrangement of equipment and tools and the interconnection with re-
frigerant hoses for drawing a vacuum at the system and finally charging with re-
frigerant. These are activities in general where flammable refrigerant can be
present. Please refer to page 75 and respect the temporary flammable zones for
your intended work activities and arrange for the safety area of 2 metres within
your work space (see page 74). Keep in mind that before evacuation and
charging of the system, the filter-drier has to be changed.
The process of drawing a vacuum (evacuation)
Before charging a refrigerant circuit of any RAC system with refrigerant, a
good vacuum should be drawn. This is in general to remove non-condensable
gases, such as air, nitrogen or forming-gas and to dehydrate the system. Under
no circumstances shall the system compressor or another refrigerant compres-
sor be used as a vacuum pump. The reason for this is, on the one hand a refrig-
erant compressor cannot achieve the vacuum required and on the other hand,
the AC systems compressor can be damaged by operation in a vacuum.
Favourable equipment specifications for system evacuation are as follows:
1. Always use a dual stage vacuum pump equipped with gas ballast valve and
appropriate to the volume of the refrigerant circuit (about 170 litres/minute or
6 CFM) and the capability for an ultimate vacuum of 15 micron (0.020 mbar).
2. The vacuum pump should have ⅜ ” and ¼” male flare connections
3. At best, the vacuum pump should have a solenoid valve at the suction port
to avoid any draw-back of air into the system due to a power cut during op-
eration.
4. The vacuum pump should have an oil-mist filter at the outlet with connection
for the Hydrocarbon vent hose.
5. The vacuum pump should be regularly checked for sufficient and clean vac-
uum pump lubricant.
6. For system evacuation, the vacuum pump should be connected and oper-
ated at the low– and high-side of the system. The operation of a vacuum
pump at the GREE HC Air-conditioner, the connection to the low-side only is
possible (service port provision).
7. In order to achieve the best efficiency of the pump, according to the pumps
capabilities, the vacuum hose should be of the largest diameter ( ⅜ ” diameter
and 2 x ⅜ ” female flare SAE connection) and kept to a minimum length
(about 1 metre).
8. The vacuum hose should not have core depressors (pressure drop to high
within the hose during evacuation)
9. The manifold gauge set should have a valve port for the vacuum pump with
⅜ ” and ¼“ SAE male flare connection.
10. A suitable calibrated vacuum gauge (best possible an electronic device)
shall be connected to a point on the system furthest from the vacuum pump.
For the GREE HC Air-conditioner service, the connection at the manifold
gauge set is indicated.
Do not use the
AC-Systems
refrigerant
compressor or
a compressor
in general for
vacuum proc-
essing!
A reliable dual-
stage vacuum
pump is re-
quired!
Measure the
vacuum re-
quired with an
appropriate
calibrated vac-
uum gauge!