Chapter 19 Installation and Troubleshooting of Domestic Refrigerators and Freezers
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Using Valve Adapters
1. Clean the outside of the valve adapter with a
clean cloth.
2. Remove the dust cap from the fi tting mounted
on the compressor dome.
3. Choose the correct valve stem drive.
4. Push the service valve stem forward in the
body of the valve attachment.
5. Engage the valve stem in the valve adapter
needle.
6. Thread the valve stem portion of the valve
adapter unit into the adapter body.
7. Attach the fl exible service line to the fi tting
and leave it loose.
8. Before opening the valve adapter needle,
tighten the packing unit around the valve
stem.
9. Always test the assembly for leaks using a
refrigerant pressure of 15 psig to 20 psig
(30 psia to 35 psia or 207 kPa to 242 kPa).
Process Tube and Adapters
Many manufacturers install a small length of
tubing through the compressor’s housing so they
can evacuate, test, and charge the appliance’s refrig-
eration system during the assembly process. Such a
tube is known as a process tube. When the assem-
bly process is complete, the process tube is sealed up,
but left in the system so it can be used by a service
technician.
A service line can be attached to a process tube by
first installing a piercing valve, brazing on an exten-
sion and fitting, or by installing an adapter on the
tube. Gauges and other service equipment can then
be attached to the process tube. Review Chapter 7,
Equipment and Instruments for Refrigerant Handling and
Service, for more information about piercing valves.
A process tube adapter allows the technician to
use the process tube without soldering or brazing on
an extension or flaring the tubing. It is installed by
cutting off the sealed end of the process tube, slid-
ing the process tube adapter over the process tube,
and tightening it. The service line is then attached to
the fitting at the end of the adapter. The adapter pro-
vides a positive seal. See Figure 19-21. When the ser-
vice is completed, a pinch-off tool is used to seal off
the process tube just behind the adapter, the adapter
is removed, and the end of the process tube is then
brazed shut.
Usin n n n
Pro Tip
Install a Schrader Valve
When the refrigerant has been recovered from the
system, it is always a good practice to install a Schrader
valve fi tting in the system if it does not already have one.
Installing a permanent fi tting will make future service
work safer and easier.
Safety Note
Phosgene Gas
When brazing a pinched-off process tube on a
charged system, make sure that the high-side and
side pressures are equalized and that you are working
a well-ventilated area. If there is a leak from an improper
pinch off, heating leaking refrigerant could create harm-
ful phosgene
Pinch-Off Tool
A pinch-off tool can apply a great deal of pressure
to a small area of soft copper tubing (up to 3/8″ OD)
to seal it off. This tool can be used to isolate parts or
sections of tubing when an emergency such as a bad
leak arises. Lines should be pinched only when abso-
lutely necessary. There are several different types
of pinch-off tools. Two common types are shown in
Figure 19-22.
Another type of pinch-off tool has a screw shaft
with a ball bearing on the end that presses against the
tube. The tool is placed over the copper tubing in the
same manner as a tubing cutter. The tubing is slowly
compressed by turning the pinch-off tool handle clock-
wise. See Figure 19-23.
Install a S chrader Valv e
W hen the refrigerant has been recovered f rom the
system, it is always a good practice to install a S chrade r
valve fi tting in the system i f it does not already have one.
Installing a permanent fi tting will make f uture service
work safer and easier.
Phosgene Gas
W hen brazing a pinched-off process tube on a
charged system, ma ke sure that t h e high-side an d llow- ow-
side pressures are equalized an d that you are working iin n
a well-ventilated area. I f there is a leak f rom an improper
pinch o ff , heatin g leakin g refrigerant could create harm-
ful phosgene ggas. as.
Process tube
Flanges
Clamp and seal
Service connection
Goodheart-Willcox Publisher
Figure 19-21. Cutaway of a process tube adapter installed on
a process tube. As the two fl anges are tightened together, the
seal is compressed, causing it to expand in the center. This
creates a tight seal between the process tube and the fl ange.