Haier AU282AHBEA Service Manual page 193

After pressurizing for 24 hours, each 1 C difference of ambient temperature will result in 0.01MPa
2
(0.1kg/cm g) pressure change. It shall be corrected during test.
Checking the leaking point
From the first to third steps, if the pressure drops, check the leakage in each joint by the sense
of hearing, feeling or soap water, etc. to find the leaking point.
After confirming the leaking point, welding it again or tighten the nut tightly again.
Piping and indoor unit vacuumizing
Use vacuum pump to perform vacuumizing. It is strictly forbidden to use the refrigerant to remove
the air inside the system.
After air tightness test and discharging all the nitrogen, connect the vacuum pump as the following
figure shown.
Indoor
Completely tightened
Completely tightened
Indoor units
It shall use the vacuum pump of (lower than -755mmHg)high vacuum degree and large air
discharging (over 40l/min).
The vacuumizing time depends on the length of the connecting pipe, generally is 1~2 hours.
When vacuumizing, it shall be confirmed both gas and liquid side valves are closed.
If after 2 hours vacuumizing, it cannot reach the vacuum degree below -755mmHg, it can be
vacuumized for other 1 hour.
If after 3 hours vacuumizing, it still cannot reach the vacuum degree below -755mmHg, check
if there is any leaking point and repair the them.
If after over 2 hours vacuumizing, the vacuum degree is below -755mmHg, close the V L and V H
on the meter separator and stop vacuumizing. 1 hour later to confirm if the vacuum degree changes.
If changes, it indicates there is leaking point in the system. Check the leaking point and repair.
After finishing the above vacuumizing, change the vacuum pump into refrigerant pump to charge the
refrigerant.
3-way valve totally closed
(Gas side)
Outdoor
Flare part
Flare part
2-way valve totally closed
(Liquid side)
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Low pressure gauge
V L VH
Discharging valve
P
Vacuum pump
Outdoor units
High pressure gauge
Meter separator