closed system is opened and, unless precautions are
taken, refrigerant is lost to the atmosphere. The best
way to contain the refrigerant (gas and liquid) is to trap
it in the condenser and receiver by pumping down the
To pump down the system, proceed as follows:
1. Secure electric power to the unit and connect the
refrigerant manifold test set, as shown in figure
2. Close the receiver stop (king) valve (by turning
the valve stem inwards as far as it will go), and
close both gauges on the gauge manifold (LO
and HI valves).
3. Start the compressor and mid-seat the discharge
and suction service valves.
4. Operate the compressor until the pressure on the
suction (LO) gauge on the manifold shows a
vacuum at 0 to 1 psi.
5. Stop the compressor. If the pressure rebuilds
appreciably, operate the unit again until
pressure registers between 0 to 1 psi. Repeat
this step until the pressure no longer rebuilds
6. When suction pressure remains at about 0 to 1
pound as read on the compound gauge, then
front-seat the suction and discharge service
valves (fig. 6-56). This procedure traps
practically all the refrigerant in the condenser
RECOVERY, RECYCLING, AND
Laws governing the release of chlorofluorocarbon
refrigerants (CFCs) into the atmosphere have resulted
in the development of procedures to recover, recycle,
and reuse these refrigerants. Many companies have
developed equipment necessary to prevent the release
of CFCs into the atmosphere. Refrigerant recovery
management equipment can be divided into three
categoriesrecovery, recycle, and reclaiming
Removing refrigerant from a system in any
condition and storing it in an external container is
called "recovery." Removal of refrigerant from the
system is necessary, in some instances, when repair of
a system is needed. To accomplish this, you can use
special recovery equipment, which is now a
requirement when removing refrigerant from a system.
This equipment ensures complete removal of the
refrigerant in the system.
Recovery is similar to evacuating a system with
the vacuum pump and is accomplished by either the
vapor recovery or liquid recovery method. In the vapor
Figure 6-55.Connections for pumping down a system.