AUX air conditioner service manual
196
pressure hose with vacuum pump and vacuum the system.
②Tighten thimble head; Discharge air in the hose with refrigerant steam in system or refrigerant in
the bottle. If small refrigerant bottle has been connected with hose and vacuum pumping has been
done, there’s no need to discharge air.
③Start up air conditioner, check low pressure value when it runs stably and judge the remaining
refrigerant in system. Open valve on the refrigerant bottle and then refrigerant enters into refrigerating
system. At the same time, we should observe and control low pressure; continue to fill the refrigerant
until pressure reaches standard evaporate pressure.
④Refrigerant from low pressure valve is in gaseous form. When gas pressure in bottle is no longer
larger than pressure in system, we shall heat the bottle with warm water so as to promote gaseous
pressure in bottle and push refrigerant continue to flow into system. Do not stand refrigerant bottle
upside down to avoid liquid slugging accident.
⑵Add refrigerant with high pressure valve
Connect high pressure valve to special hose (with thimble) to add refrigerant. Tighten thimble head,
discharge air in the hose, and then stand the refrigerant bottle upside down and open bottle valve,
liquid refrigerant will flow into high pressure side of air conditioner. When pressure in bottle is no
longer larger than that in system, refrigerant will stop to flow into system. Heat the bottle with warm
water to promote pressure in bottle, and then liquid refrigerant continues to flow into system. The
whole operation process is conducted when compressor is switched off.
High pressure filling method shall be used to fill relatively large air conditioner or air conditioner by
using liquid reservoir. To control refrigerant filling volume, usually a weighing appliance will be used.
If no weighing appliance is available, refrigerant volume shall be controlled based on experience. For
the equipment without reservoir or requiring accurate filling volume, we can connect filling appliance
with low pressure valve, add or release part of refrigerant by using the same steps as the said low
pressure valve filling method.
⑶Determination of refrigerant volume
At present, R22 refrigerant is commonly used in household air conditioner. According to the thermal
feature, under normal work condition of air conditioner, volume of refrigerant shall be calculated as
per following parameters:
① Low pressure: evaporate pressure shall close to pressure on return gas tube of compressor which is
0.5MPa(absolute pressure 0.6MPa), and the evaporate temperature is 5℃;
② Return gas temperature: temperature on the return gas tube of compressor shall be within 7℃~15
℃, condensate instead of frost can occur on the return gas tube;
③ Running current: Generally running current of compressor shall not exceed rated value on the
nameplate;
④ Indoor unit air inlet and outlet temperature difference: In cooling operation, temperature difference
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