MACS Monthly Newsletter - 2022 - JUN7

More than one leak? Maybe not.
The 2009 Honda Fit came into
the shop with the " no A/C cooling "
complaint and the technician
could hear the clutch was making
noise. The customer was anxious
to get the car back ASAP (isn't
everyone?). The technician was
able to get a good price on a new
replacement (OE) compressor, so
that was what he chose to install
instead of just a clutch replacement.
He vacuum-pumped the
refrigeration system for an hour,
then recharged it with 14 oz of R134a,
and cooling was normal - for
just a few days, however. It came
back with a clearcut drop in cooling
performance and the clutch
cycling every few seconds. This
time he also went over the system
with an infrared SAE-certified electronic leak
detector and found a leaking joint at the brand-new
compressor, which the parts jobber replaced. Once
more he installed the compressor and recharged it
with 14 oz of R-134a and cooling was normal, again
for just a few days. Did he miss a leak? He went over
the system once more and could find no leak. However,
although his R/R/R machine was seemingly
in physically good condition, it was over 15 years
old. So " just to cover all the bases " he pulled out
his manifold gauge set, put his refrigerant jug on a
scale and (for good measure) recharged with 15 oz
(the factory spec is 14.8 oz, so rounding up made
sense). Once again, the system cooling was good
and this time the car didn't come back, so there was
now a reason to suspect a fault with the machine.
The SAE certified (to SAE J2788) refrigerant recovery/recycling/recharge
machines were introduced
some 17 years ago, and in a busy shop (this
one is), the early ones may have reached the end
of their high-accuracy life. They were the first machines
to come with a way to check the accuracy
of their scales, using a calibration weight and an
algorithm in the machine's control panel. Sadly,
the calibration weight was lost, so the shop hadn't
checked scale calibration in eons. And after years of
being rolled around the shop floor, hitting some uneven
sections, eventually the scale calibration was
affected. Add in lack of maintenance, such as failure
to change the vacuum pump oil regularly, and loss
of accuracy is not surprising.
So, if you have an old R-134a machine that may
show signs of deterioration, and now are getting a
lot of R-1234yf cars also into your shop, it may be
time for a new machine. And you haven't bought an
R-1234yf machine, maybe you should be investing
in a dual refrigerant machine that meets the SAE
J3030 standard, covering service of both refrigerants.
And give it good care. v
June 2022
7
MACS Service Reports
MACS Monthly Newsletter - 2022

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