MACS Monthly Newsletter - 2020 - AUG3

widely used in Europe, where some countries prohibit
injecting refrigerant into a leaking system, so tracer gas
is the only alternative. But we're not sure that's a great
recommendation, because the tracer gas detectors
were in use well before an SAE-certified and validated
detector was available.
4. We also recognize there are other possible workarounds that involve not using the RRR machine but
other ways of injecting refrigerant into the system.
However, if there's a gross leak, No. 1 is the way to

go. It ensures you will not be wasting a lot of refrigerant, and most important, that you'll be getting just
enough into the system for leak detection if you have
a premium, certified SAE J2913 (or J2791, which was
certified for R-134a) leak detector, and if you use it
properly. Our best results always have been with an
infrared type, and so that's what we've always recommended. Make sure it's operating correctly before you
start installing R-1234yf. n

A/C FITTINGS AND SEALS
fix leakage that used to be considered normal. Which is
why the current generation of electronic leak detectors
that meet the newest standards (SAE J2791 for R-134a
and J2913 for R-1234yf) are calibrated to trigger when
they detect leaks of as little as 4 grams/year.
Toyota is one of the few car makers that doesn't approve use of trace dye, so unlike many manufacturers,
it doesn't install dye on the assembly line. To minimize
comebacks, it recommends close inspection of joints if
an SAE Certified (J2791/J2913) electronic leak detector
alarms when the probe slowly sweeps by.
When a leak occurs at a joint connection, attention often
is focused on the elastomer seal, which typically is one or
more O-rings or a gasket. Or the joint may use a metallic
seal with an O-ring or a combination metallic-elastomeric
seal, most popularly in the form of a seal washer (Figure
4). Until recently, many joints were connected with the
once-notorious spring lock coupling assembly. Actually,
the tightening of tolerances on the spring-lock and locating it at a rigid point in the refrigerant circuit made it a
reasonably good way to seal a joint by the time it was
discontinued.
As tight as a seal joint design may be, even when it's

amazon.com

techinfo.toyota.com

Just as soon as a common service issue is fixed by the
car makers, it seems to find a way to resurface in another
way. Refrigerant leakage is doubtlessly the most frequently seen example. If you've been in this industry a while,
you may remember how much of a problem refrigerant
hoses were. They admitted moisture and the desiccant
packs would hold just so much, then free moisture in the
refrigerant system would freeze, and cooling would stop.
The hoses also admitted air and allowed refrigerant to
leak out. When the industry switched to barrier and veneer hoses of various designs, many of those issues were
eliminated, although hose crimp leakage periodically
surfaces as an issue.
However, one area has emerged, and continues to be a
sealing problem: O-rings. For the most part, refrigerant
joint seals in recent years have been very tight, and their
performance enabled the car makers to claim emission
credits toward CAFE (Corporate Average Fuel Economy)
standards.
But with the average age of cars on the road now at 12
years, deterioration of seals from the effects of weather,
component vibration and underhood and underbody
splash of abrasive road film, it's hardly surprising that Oring joints will leak. They may not leak a lot, but smaller
refrigerant charges and systems with less margin for loss
of refrigerant as a result, mean that you have to find and

Figure 5: Refrigerant line vibration, temperature changes
and airborne debris cause deterioration of O-rings in refrigerant joints.

Figure 4: : A/C sealing washers, which combine elastomeric seal with
metal washer, provide a wide sealing surface.

August 2020

MACS Service Reports

http://techinfo.toyota.com http://www.amazon.com

MACS Monthly Newsletter - 2020

Table of Contents for the Digital Edition of MACS Monthly Newsletter - 2020