WD Catalog 2018

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12-3 - -
1. Using your R-12 recovery/recycle equipment, remove the R-12.
2. Remove mineral oil. Removing as much mineral oil as possible is
very important, although some tests indicate a residual amount of
oil can be tolerated.
3. Discard the receiver-drier.
4. Make efforts to drain those components where lubricant may
collect. This would include evaporator coils and the lowest hoses
such as those routed to a sleeper box evaporator.
5. If you are reusing the compressor, it should be removed and
drained. Measure the amount of oil removed.
6. Power flushing with R-12 might be considered, but to be success-
ful, system restrictions (compressor, receiver drier, and expansion
valves) must be isolated. Other solvents may not be compatible
with system components, R-134a or the new lubricants. Know for
sure what you are using, and use only what is approved by the
system’s manufacturer.
WARNING Compressed air should never be used to flush or
purge a system. Although compressed air is most dan-
gerous in the presence of R-134a, bad habits could
develop with R-12 and carry over to the new refriger-
ant. Compressed air almost always contains moisture
which could result in early comebacks and additional
cost.
7. New quick connect service fittings must be installed on an R-134a
system. This is done to prevent servicing with refrigerant other
than R-134a. Figure 12-1 shows these fittings.
QUICK CONNECT HOSE END FITTING
WITH INTEGRAL SHUTOFF VALVE
SERVICE HOSE CONNECTION
DEPRESSOR PIN
SYSTEM SERVICE PORT
VALVE ASSEMBLED TO SERVICE PORT WITH VALVE IN THE OPEN POSITION
8. Reassemble the system with its new components. Attach a
vacuum pump and evacuate for at least one hour. Leak check as
discussed in Chapter 9.
9. If a label identifies the amount of R-12 and lubricant that was
used in the system, replace with that amount.
General Retrofit Procedure
Figure 12-1
This illustration shows
R-134a service ports and
hose end fittings.