“That” isn’t some unnamed
mystery. Some shops still use R-11 and R-113 as flushing agents (they
haven’t been produced in eons in the U.S., but there seems to be a lot
around). These flushes worked great on CFC-12 systems, but when some
early attempts at retrofit to HFC-134a failed miserably, one cause was
trace amounts of them. R-11 and R-113 are considered “secret weapons”
pulled out and used for some really contaminated HFC-134a systems.
The technician figures
they were great on those old CFC-12 systems, so they also will really
clean up total failures today. Ditto for some aftermarket flushes, but
with a somewhat different slant. Reputable aftermarket flushes may be
helpful with minor amounts of debris and oil removal, particularly
those used with closed-loop flushing machines and air purges. Shops
see they remove debris and push the envelope.
But when it comes to a
catastrophic failure, even R-11 in the CFC-12 days often wouldn’t do
the job, and the condensers of the CFC-12 days had much larger tubes
than today’s models with passages the diameter of a toothpick or
smaller. When reputable aftermarket suppliers today talk about
catastrophic failures, they typically have a long list of parts to
replace, and filters to install. They may recommend their flush only
for some parts of the job.
Doesn’t Ford recommend a
specific terpene flush for catastrophic failures? Within certain
limits, yes, but only as part of a comprehensive procedure, which
we’ll talk about in “CLASSIC CASE,” the case history of a late model
Ford rear-drive car (Crown Victoria/Grand Marquis) that follows.
Ford’s flushing procedure
is specified with a particular flushing machine, with a lengthy air
purge. Does that really matter? Yes, if you plan to use a Ford shop
manual procedure on a Ford vehicle. Ford never tried any aftermarket
flush and doesn’t know under what conditions it works and doesn’t work
for major contamination, or what procedure might be required. When
Ford validated its flush, it determined the amount of time needed to
circulate the solvent for debris removal, it tested the air purge
procedure often enough to be sure that only the most minor trace might
be left in, and that the trace did no harm.
Further, as Ford
condensers went through design improvements, with tinier passages and
more flow paths,
Ford recognized that with
catastrophic failure it might not always be possible to include the
condenser in that flushing operation, in which case replacement was
necessary.
So as noted earlier, shops
that don’t replace with an OE level condenser, could see
higher-than-normal head pressures and in hot weather, premature
compressor failures. If you don’t put price first, you can get OE-level
condensers, and many shops do, from reputable suppliers. But we find
out about shops that do so many things so well, but take shortcuts
when dealing with catastrophic failures. We understand the impetus:
many parts to replace, much work to do, and the price edges up to the
area where there’s
customer resistance. So
using some cheaper parts lowers the total, whether it’s with the
condenser, a questionable compressor, a make-it-fit evaporator and an
old favorite: flushing hoses with mufflers, instead of replacing them.
Hoses with mufflers can’t
be flushed successfully. To quote Ford: “hoses without mufflers can
normally be reused unless they are clogged with foreign
material...Install new refrigerant hoses with mufflers if clogged with
foreign material.” You can’t tell without cutting apart, so just
replace.
Another approach that’s
even worse: just blowing shop air through the hoses, and when the air
comes out the other end, deciding to re-use the hose – sorry, shop air
(or dry nitrogen) through a hose isn’t flushing. But even a flushing
agent blown out of a spray gun may not completely clear a hose after a
catastrophic failure. It’s not that the hose still is packed—it
probably isn’t, but as the remaining debris flakes off from the walls
of the hose, and gets carried to the compressor (or even as far as the
expansion valve), it’s not going to improve compressor life or
performance. That’s why cautious shops that flush suction hoses also
install suction side screens.
Remember the old problems with suction hoses in which the inner liners
collapsed? You could cut those things apart and see the necked-down
areas, but you might find it hard to believe the seemingly small
amount of reduction in diameter was responsible for major loss of
performance – but it was.
