7–3
T-372
With the valve stem midway between frontseat and backseat, both of the service valve connections are open to the
access valve path. For example, the valve stem is first fully backseated when connecting a manifold gauge to mea
-
sure pressure. Then, the valve is opened 1/4 to 1/2 turn to measure the pressure.
Figure 7.3 Service Valve
1) Access Valve
2) Step Cap
3) Valve Stem
4) Compressor or Filter Drier Inlet
Connection
5) Line Connection
- - - - -
Connection of the manifold gauge / hose set (see
) is dependent on the component being serviced. If
only the compressor is being serviced, the high side coupling is connected to the discharge service valve.
For service of the low side (after pump down), the high side coupling is connected to the liquid line service valve.
The center hose connection is brought to the tool being used (vacuum, tank, etc.).
7.3.1
Connecting the Manifold Gauge Set
1. Remove the service valve stem cap and make sure the valve is backseated.
2. Remove the access valve cap (see
).
3. Connect the field service coupling (see
) to the access valve.
4. Turn the field service coupling knob clockwise to open the system to the gauge set.
5. Slightly midseat the service valve to read system pressures.
6. Repeat the procedure to connect the other side of the gauge set.
CAUTION
!
To prevent trapping liquid refrigerant in the manifold gauge set, make sure set is brought to
suction pressure before disconnecting.
7.3.2
Removing the Manifold Gauge Set
1. While the compressor is still ON, backseat the high side service valve.
2. Midseat both hand valves on the manifold gauge set and allow the pressure in the manifold gauge set to be
drawn down to low side pressure. This returns any liquid that may be in the high side hose to the system.
3. Backseat the low side service valve.
4. Backseat both field service couplings and frontseat both manifold hand valves.
5. Remove couplings from the access valves.
6. Install both service valve stem caps and service port caps (finger-tight only).
7.4 Pump Down the Unit
To service the filter drier, economizer, expansion valves, economizer solenoid valve, digital unloader valve or evap
-
orator coil, pump the refrigerant into the high side of the unit:
5
1
2
3
4
Valve (Frontseated)
Valve (Backseated)
