■Basic Function of the Service Valves
The basic function of the service valves are given in Table 7 below.
Table 7
Action | Narrow Tube Service | Wide Tube Service | ||
Valve | Valve | |||
| ||||
| CLOSED | Valve cap | ||
|
|
| Stem | |
Shipping
Fully OPEN
Operating and test running
the air conditioner
| Fully OPEN |
Measuring pressure | * |
and gas charging |
|
| CLOSED |
Air purging with | * |
a vacuum pump |
|
*The service port on the wide tube service
valve uses a Schrader core valve to access | Service valve | |
Hose with | ||
the refrigerant system. Therefore, be sure to | ||
use a hose connector which has a |
| |
inside. (Fig. 55) |
|
PUSH
■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
Fig. 55
valve clockwise all the way to close the service valve. (Be sure to confirm that the wide tube ser- vice valve is fully open.)
(3)Press the operation button and start cooling opera- tion.
(4)When the low pressure gauge reading falls to 1 to 0.5 kg/cm2 (14.2 to 7.1 PSI), fully close the wide tube valve stem with a standard screwdriver. Then quickly stop the unit.
(5)Disconnect all gauges and hoses, and replace the bonnets and the valve caps as they were before.
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