Carrier 69NT40-561-300, Operation And Service Manual

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7–3 T-365
Figure 7.3 Service Valve
Connection of the manifold gauge/hose set (see Figure 7.4 ) 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.).
Connecting the manifold gauge set:
1. Remove service valve stem cap and to make sure the valve is backseated.
2. Remove access valve cap (See Figure 7.3 ).
3. Connect the field service coupling (see Figure 7.2 ) to the access valve.
4. Turn the field service coupling knob clockwise, which will open the system to the gauge set.
5. To read system pressures, slightly midseat the service valve.
6. Repeat the procedure to connect the other side of the gauge set.
CAUTION
!
To prevent trapping liquid refrigerant in the manifold gauge set be sure set is brought to suc-
tion pressure before disconnecting.
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. Backseat both field service couplings and frontseat both manifold hand
valves. Remove couplings from access valves.
4. 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 loader valve, digital
unloader valve or evaporator coil, pump the refrigerant into the high side as follows:
CAUTION
!
The scroll compressor achieves low suction pressure very quickly. Do not use the compressor
to evacuate the system below 0 psig. Never operate the compressor with the suction or dis-
charge service valves closed (frontseated). Internal damage will result from operating the com-
pressor in a deep vacuum.
Line Connection
Access Valve
Stem Cap
Valve Stem
Compressor of Filter Drier Inlet Connection
Valve (Frontseated) Valve (Backseated)