Toshiba MM-A0160HX, Service Manual

Page: 106 / 135

107
17
Refrigerant Pipe Installation
Vacuuming
(1) After the airtight test, discharge nitrogen gas.
Connect a gauge manifold to the service ports at liquid, gas and balance sides, and
connect a vacuum pump as shown in the following figure.
Be sure to perform vacuuming at liquid, gas, and balance sides.
(2) Use a vacuum pump with a large displacement so that the vacuum will achieve
below –755mmHg.
(3) Perform vacuuming for 2 or 3 hours, though time requirement differs due to pipe length.
During this time, check that all packed valves at liquid, gas, and balance sides are fully
closed.
(4) If vacuuming does not reach –755mmHg or below even after vacuuming for 2 hours or
more, perform vacuuming for a futher hour.
If vacuuming still does not reach –755mmHg after 3 hours, check for leakage.
(5) When vacuuming reaches –755mmHg or below after vacuuming, fully close valves.
Close V
L
and V
H
on the gauge manifold fully, stop the vacuum pump. After 1 hour check
the vacuum gauge reading has not change. If there is a change, there may be a leak.
Check for leak.
(6) After the above procedure of vacuuming has completed, replace the vacuum pump with a
refrigerant cylinder, and advance to additional refrigerant charging work.
Detailed drawing of packed valve
To gauge manifold
{
Liquid-side
service port
Liquid-side
packed valve
Balance
service port
Balance
packed valve
Piping
at site
Gas-side
service port
Gas-side
packed valve
Piping at site
Piping
at site
To main unit
To main
unit
To main
unit
Connected to Indoor Unit
Connected to other fixed-speed Outdoor Unit
Packed valve fully
closed (liquid side)
Packed valve fully
closed (balance)
Inverter Outdoor Unit
Service
port
Service port
Gauge
manifold
Vacuum pump
Packed valve fully
closed (gas side)
Fully
closed
Fully
closed
Brazed
Low-
pressure
gauge High-
pressure
gauge
Main pipe
V
L
V
H