50 Auto Heating & Air Conditioning
Orifi ce Tube Tools
Many systems require an orifi ce tube tool to remove
the orifi ce tube from the evaporator inlet. A typical orifi ce
tube tool is shown in Figure 3-25. To use the orifi ce tube
removal tool, the refrigeration system must be discharged.
Once the refrigerant is removed, disconnect the fi tting at
the evaporator inlet and insert the orifi ce tube tool. Slightly
turn the tool to engage the tangs of the tool and tube, then
withdraw the tube. To install the new orifi ce tube, place it
on the tool, then insert the tool and tube into the evaporator
inlet. Slightly twist the tool to disengage it from the tube,
then withdraw the tool.
Oil Injectors
Oil injectors are used to install lubricating oil in the
refrigeration system without discharging the system. There
are two kinds of oil injectors in common use. To use the
type shown in Figure 3-26A, fi ll it with the proper type of
compressor oil. Then with the HVAC system off, install the
injector service fi tting. Turn the forcing screw at the top of
the injector to force the oil into the system. Then remove
the injector from the fi tting.
Another type of oil injector, Figure 3-26B, is installed in
the hoses of the gauge manifold. To use this type of injector,
pour the proper type of oil into the reservoir. Then attach
the oil injector to one of the manifold hoses. Attach the
hoses to the refrigeration system and purge the hoses and
injector as necessary. Then start the engine and place the
HVAC system in maximum cooling. Allow the refrigeration
system pressures to stabilize. Next, slightly open the high
and low side valves. The difference in pressures will force
the oil into the low side of the refrigeration system. Allow
the system to operate long enough for all oil to enter the
system, then close the valves and remove the injector and
gauge manifold from the refrigeration system.
Refrigerant Service Equipment
The following section covers large shop equipment
used to service the refrigeration system. During air con-
ditioner service, the refrigeration system may need to be
emptied of refrigerant, fl ushed of contaminants, placed
under a vacuum, and recharged.
Figure 3-21. A—Nitrogen should be used to check for leaks.
Nitrogen is an inert gas and will not harm the atmosphere.
B—Adapters are used to check hoses for leaks.
B
A
Figure 3-22. Bench mounted hose cutters will make a clean
straight cut. Some technicians prefer to use a hand cutter.
Figure 3-23. Manual crimping tools can be used to make accept-
able hose connections. However, most technicians prefer to use
power crimping tools to ensure a leak proof seal.