21
Pump Down
Pump down means collecting all refrigerant gas in the
system back into the outdoor unit without losing any of
the gas. Pump down is used when the unit is to be
moved or before servicing the refrigerant circuit.
Pump Down Procedure
Be sure to carry out pump down with the unit in
Cooling mode.
(1) Connect the Lo side charging hose of the manifold
valve to the service port on the wide tube service
valve.
(2) Using a hex wrench, turn the narrow tube service
valve clockwise all the way to close the service
valve. (Be sure to confirm that the wide tube service
valve is fully open.)
(3) Press the operation button and start cooling oper-
ation.
(4) When the low pressure gauge reading falls to 14.2 to
7.1 psi (1 to 0.5 kg/cm
2
), fully close the wide tube
valve stem. Then quickly stop the unit.
(5) Disconnect all gauges and hoses, and replace the
valve caps as they were before.
Basic Functions of the Service Valves
The basic functions of the service valves are given in Table 7 below.
Action
Narrow Tube Service
Valve (2-Way)
Wide Tube Service
Valve (3-Way)
CLOSED
Fully OPEN
Fully OPEN
Shipping
Operating and
test running
the air conditioner
Measuring pressure
and gas charging
Air purging with
a vacuum pump
CLOSED
Valve cap
Stem
O-ring
*
*
Table 7
*
The service port on the wide tube ser-
vice valve uses a Schrader core valve
to access the refrigerant system.
Therefore, be sure to use a hose con-
nector which has a push-pin inside.
(Fig. 32)
PUSH
Hose with push-pin
Service valve
Fig. 32
Close
Hex
wrench
Open
Fig. 33
CAUTION
When opening or closing
the service valve stem,
use the hex wrench.
Be sure to fully seat the
wrench before turning
the valve.
External diameter of service port
R410A: 5/16"
NOTE
