MACS Monthly Newsletter - 2017 - NOV5

Alldata

He checked back with the customer first, of course, and
then gets an interesting piece of information. At some time
in the past the Murano got a replacement evaporator, and
because the job was done at an independent garage, it likely
was an aftermarket unit. However, the technician checked
through the case with an electronic detector, and there apparently was no leak at the evaporator core. Are you thinking, another case of an inferior replacement part? Well, our
experience is that the typical aftermarket heat exchanger is
likely to be pretty good. But with the customer's authorization, the technician goes into the case and finds that indeed
it was a quality aftermarket evaporator, but it was just a bit
smaller than the OE unit; probably not enough smaller to
have a major effect on cooling. Although of course, its internal design might have been short of the OE one. However,
the installing shop had filled the gap in the HVAC case with
plumber's putty, apparently pretty well. But when the expansion valve was replaced, this created enough movement
to dislodge the putty and create an air gap for much of the
airflow to go over the evaporator core instead of through it.
See Figures 6, 7.

Figure 7: Remove retaining bolts, work expansion valve from firewall, then
install replacement. In the case of the Murano, the movement of the expansion valve was sufficient to dislodge the putty that filled the gap between the
aftermarket replacement evaporator and the HVAC case.

Alldata

This would often create a "who's responsible" situation.
The technician didn't know about the aftermarket core, so
it's hard to blame him for what was probably normal movement of the evaporator when he worked underhood to
change the expansion valve. Fortunately, the customer decided that inasmuch as the technician already had gone into
the HVAC, he would pay for replacement of the aftermarket
evaporator with an OE core. With the new core, the A/C register temperatures dropped into the low 40's, and it all ended
well.
If you do decide to install an aftermarket evaporator that
leaves a small gap, the moral of this story is to use a more
durable way to close the gap, such as a foam strip with a
really good adhesive. With R-1234yf systems at this early
stage, you probably won't find an aftermarket replacement
evaporator that meets SAE J2842, which sets the testing requirements for system safety with the mildly-flammable refrigerant. However, there's a wide choice of evaporators for
R-134a systems, and that's most of the market to date. ■

Figure 6: Removing expansion valve assembly from under the hood. Loosen
retaining bolt and disconnect low-pressure and high-pressure lines.

LATE MODEL FROM A BODY SHOP
When a late-model car comes to an A/C specialist, it's very often from a body shop with whom it has a working relationship.
In most cases there has been front end damage, and the body
shop already has replaced some parts from the front end cooling
module, typically including the condenser and often the radiator and any other heat exchangers that took an impact. Most of
the time, the body shop is looking for little more than a system
recharge.
In this case (a 2016 Kia Sorento with the 2.4-liter four-cylinder),
the body shop installed replacement parts for damaged A/C refrigerant lines and a hose, and also had done the recharge itself.
However (and we're sure that some readers are happily snickering about this), the A/C clutch would not engage, and diagnosis
of this basic issue was obviously beyond the capability of the
body shop.
The system took a full charge and held it, so a leak at the
condenser's inlet and outlet fittings, which is pretty com-

November 2017

mon when the job is done by a body shop, was not the issue. This one was electrical, and the technician found no
power or ground at the compressor connector. He saw the
high-pressure switch, and it had a good ground. As a routine check, he also ensured all the body and battery grounds
were clean and tight.
He next went to the Alldata service information for HVAC,
which was straight from the Kia online system. First thing
he found was a procedure, including parts, prices and labor,
for the compressor clutch (Figure 8). He wasn't sure he was
going to do a clutch replacement. We recognize that many
shops today do not, although it's often cheaper even with
the shop labor factored in, and if you're willing do it, it's not
a big deal. If you lift the hood and look, you might not see
much of the front of the compressor. But if you remove some
parts, you may have sufficient access to reach the front of the
compressor and replace the clutch.

MACS Service Reports

Table of Contents for the Digital Edition of MACS Monthly Newsletter - 2017