MACS Service Reports - 2015 - OCT8

es it just because he can. The replacement, by the way, includes applying a dab of silicone grease to the base of the switch
before installation (Figure 14). The system seems to work for a
few days, but comes back again.
This time the technician tries a wiggle test on the wiring to
the clutch coil. Earlier in his diagnosis he did get 12 volts and
a good ground, but this time he got a seeming intermittent. He
follows up with an ammeter hookup and a repeat of the wiggle

test. Finally, he gets a reading that indicates an open circuit, and a
new clutch coil fixes the problem. Would reducing the clutch air
gap to something close to the minimum have helped? It certainly might have lengthened the time between intermittents and
could have indicated that the clutch coil was weak. The bottom
line seems to be: when it comes to the clutch circuit, almost anything is possible and you may find yourself trying everything in
the book. ■

TAKE A VEHICLE HISTORY

prodemand.com

Learn to read a customer's face, because many don't want
to talk about work done at another shop. The car may be a
relatively recent purchase, and the ownership period may
not include the last peak of the air conditioning season.
Here's what should be a pretty easy one to diagnose: a
2007 Suzuki SX4 with the 2.0-liter four cylinder. The motorist complaint is that the air stops blowing but there is an air
rushing noise. Every time the customer comes in with the
car (three times so far), there is no problem; it cools just fine.
She has owned the car from mid-Fall through to the start of
A/C season, so that fits into the no-previous-peak period
of usage. No real history to take, but if she could reach the
previous owner, she might have saved the shop a lot of diagnostic grief.
The car has no intake air filter, so that's ruled out, but this
time she drives the car in the shop's area and comes in with
the system running and the problem present. She had the
symptoms right, and the issue actually is what you may be
thinking: evaporator icing. She is able to reach the previous
owner and amazingly he tells her that he had the same problem, but had it repaired.
The fix was replacement of the evaporator temperature
sensor, so now they're thinking it must be defective. Aftermarket information systems do provide the Suzuki OE sensor resistance specs (Figure 15), and an ohmmeter test indicates the sensor is good.
Now what? The shop's belief is that the symptom still says
the sensor is the problem, so it takes a look around the evaporator case with a borescope (good reason to have one). As it
turns out, the sensor was virtually out of its retaining slot in
the evaporator core, and proper reinstallation (in a close-by
slot) finally solves the problem. ■

Figure 15: Suzuki provides resistance specifications for testing the evaporator temperature sensor, in this case a 2007 model.

MACS Service Reports is published monthly by the Mobile Air Conditioning Society Worldwide. It is distributed to members of MACS Worldwide
and is intended for the educational use of members of the automotive air
conditioning service and repair industry. Suggestions for articles will be
considered for publication, however, MACS Worldwide reserves the right
to choose and edit all submissions.

Editors:
Elvis Hoffpauir, Steve Schaeber
Production Designer:
Laina Casey
Manager of Service Training:
Steve Schaeber
Mobile Air Conditioning Society Worldwide
P.O. Box 88, Lansdale, PA 19446
Phone: (215) 631-7020 * Fax: (215) 631-7017
Email: membership@macsw.org * Website: www.macsw.org

Unless otherwise noted, all photos/art by author.

October 2015

MACS Service Reports

http://www.prodemand.com https://www.youtube.com/user/MACSWorldwide https://plus.google.com/109580133945503595889 https://macsworldwide.wordpress.com/ https://www.facebook.com/MACSW https://www.linkedin.com/start/join?trk=login_reg_redirect&session_redirect=https%3A%2F%2Fwww.linkedin.com%2Fgroups%2F1759747 https://www.twitter.com/MACS_Worldwide http://www.macsw.org

Table of Contents for the Digital Edition of MACS Service Reports - 2015