LG Multi F A2UW14GFA0 Engineering Product Data Book page 328

2. Guideline for each installation process
2.7.4 Vacuum drying procedure
There are two vacuum drying methods and the appropriate one should always be chosen to confirm with individual local
conditions.
[Normal vacuum drying]........The standard method
[Operational steps]
① Vacuum drying (1st time): Connect a manifold gauge to the service port of the liquid or gas pipe and operate the vacuum
pump for at least 2 hours.
(The degree of vacuum produced should be in excess of 5 Torr)
If after 2 hours the vacuum produced has not exceeded 5 Torr then either there is moisture in the pipe or there is a leak.
Operate the vacuum pump for further one more hour.
If, even after 3 hours, the vacuum has not reached 5 Torr then check the system for a leak.
② Carry out vacuum test.
Produce a vacuum in excess of 5 Torr and do not release it for an hour or more. Check the vacuum gauge to make sure
that it has not risen. (If the gauge rise then there is still moisture in the pipe or there is a leak somewhere.)
③ Additional charge of refrigerant.
Connect the charging cylinder to the liquid pipe service port and charge with the required amount of refrigerant.
④ Open stop valve to the full.
Open the stop valve on the liquid and the gas pipes to the full.
NOTE
Vacuums should be produced in both the liquid and the gas pipes.
(Because there are a large number of functional components in the indoor unit which cut off the vacuum mid-way through)
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Heat pump 50Hz/R410A