The compressor on the 2004
Crown Vic failed and the technician saw contamination, so (he said) he
“replaced every component” with the OE parts (supposedly including
condenser, evaporator and every line and accumulator)
During assembly, he added
oil to each, and finally charged the system (accurately of course). He
ran the A/C and the gauge readings started oscillating. He found the
orifice tube loaded with metallic debris, after just seconds of
operation. He replaced the compressor twice more, along with
accumulators and orifice tubes, and sadly got the same problem each
time. With a fourth compressor and assorted other new parts, the
failures seemed to have stopped.
We weren’t there, standing
by the technician’s side, to document everything he claimed was done.
If the gauge readings were jumping, the problem recurred in minutes,
and the orifice tube was found to be loaded, debris still was in the
system. As we pointed out, when all replacements aren’t done in one
job, debris may move, and create a blockage.
Ford has long advocated
flushing the evaporator, hoses and lines, and as we said earlier, also
accepted the idea that a late-model condenser has such small passages
that it probably can’t be flushed very well if there is catastrophic
failure of the compressor. But let’s review exactly what Ford
recommends:
• After recovering the
refrigerant, disconnect the refrigerant hoses or lines from the heat
exchanger(s) to be flushed. Remove the accumulator or receiver-dryer,
expansion valve or orifice tube and hoses with mufflers. Yes, after
you find a failed compressor, you take off all these parts before you
go further.
• Attach the Ford-approved
flushing machine or one you know does an equivalent job, following the
instructions and using one fresh gallon of the approved solvent (or a
reputable terpene solvent with similar vapor and other
characteristics). Ford prescribes a back-flushing procedure, and
points out that you’re not necessarily trying to get out just
particulate debris, but oil that sludged from overheat.
• Run the flushing solvent
through the heat exchanger for at least 15 minutes, more if there’s
likely to be a lot of debris.
Then air purge for at
least 30 minutes. Ford warns: ”Failure to successfully remove all
residual solvent within the component can result in system damage when
reconnected and (the system is) operated.” Never shorten the air
purge, ever on any machine.
• If the problem was a
failed compressor or desiccant, replace the accumulator or
receiver-dryer, the orifice tube or thermal expansion valve (or clean
or replace the TXV screen) and hoses or lines with mufflers.
• “If A/C system
contamination is extensive,” Ford recommends using a pancake filter
kit, installed with auxiliary hoses in series with the condenser and
its outlet line fitting. Run the A/C; engine idling for several
minutes at 800 r.p.m., then for several minutes at 1000 r.p.m. and
finally (for an hour) at 1200 r.p.m. Then discard the filter. The
appeal of this filter is that it doesn’t require cutting into a line
for a permanent installation, but remember it’s been validated only to
follow the Ford flushing procedure on Ford vehicles.
Adding a suction side
screen and a permanent in-liquid-line filter is not required by Ford,
but there’s no objection to the extra protection. The Ford flush
removes virtually all oil from components, so remember to add the
specified amounts, as noted earlier in this report.
