MACS Monthly Newsletter - 2017 - JUL1

Total Vehicle Climate and Thermal ManagementTM

July 2017

By Dave Hobbs - MACS Field Correspondent

IS IT REALLY THE COMPRESSOR?
My nephew Andrew is a fine computer expert but
knows just enough about automotive topics to change
oil, wiper blades and headlamps w/o hurting himself.
Yesterday I got the text that every professional technician
receives occasionally from friends and relatives; "I'm getting this and that done to my car. Is "X" dollars a fair
amount to pay?" Since Andrew didn't state the make
and model of his vehicle he received the usual short and
vague answer regarding price. What I did expand on,
however, was the importance of a proper A/C compressor replacement procedure. Not following routine best
practices can lead to the heartache of repeat compressor
failures. The mechanical side of best practices has been
covered quite thoroughly by MACS publications and

training. (Figures 1A & 1B) Let's take a very quick review
of just a few basic compressor R&R mechanical best A/C
practices to whet your diagnostic appetite:

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1. Proper oil balancing of the replacement compressor and system. I still run into many shops who say
"What the heck is oil balancing? New compressors
already come with oil in them."
2. Replacing the accumulator & orifice tube / receiver drier on every compressor job.
3. Proper OEM recommended flushing / condenser replacement when a catastrophic compressor
failure has occurred.
4. Adding an in-line filter / compressor inlet screen
(if applicable) in the event of a catastrophic compressor failure.
5. Choosing a quality compressor. The old saying
"cheap can be expensive sometimes!"
6. Turning the compressor shaft by hand several
revolutions prior to installation.
7. Pulling a proper vacuum (deep enough and long
enough) prior to the refrigerant charge.
8. Recharging the system with the proper charge.
That means J2788 RRR machines for applications
beyond the oldie but goodie cars and trucks that
required 3 or 4 pounds. If you're working with an
R-1234yf equipped vehicle, SAE J2843 applies of
course. Also, TSB's involving redesigned components. ■

Figures 1A and 1B: Preventing a misdiagnosis on a compressor job or a failed
compressor job, requires the extra care spelled out in MACS Best A/C Practices. If you've been to some of the live MACS Update classes (left) or viewed
the on-line webinars containing a wealth of information . . . great! However if
your human equivalent of computer "RAM" doesn't have quite the capacity
or speed it did a few years ago, there's now an app for that! The brand new
MACS Diagnostic Mobile App for your smart phone is now ready to help you
apply those best practices on the vehicle 24/7.

ALSO INSIDE THIS ISSUE:
Beating The Dead J2788 Horse? Common Scenario / Case Study ............................................................................. 2
Best Mechanical And Electrical A/C Practices................................................................................................................ 2
World Of Compressor Electrical Woes ........................................................................................................................... 2
Logic Lockup - Corruptible Software .............................................................................................................................. 3
Global Battery Resets ....................................................................................................................................................... 4
Logic Lock Up Causes / Corrections ............................................................................................................................... 4
Software Fixes ................................................................................................................................................................... 7
MACS Service Reports is the official technical publication of the Mobile Air Conditioning Society Worldwide, Inc., P.O. Box 88, Lansdale, PA 19446. The material published in MACS Service Reports expresses the views of the contributors
and not necessarily that of MACS. Every attempt has been made to ensure

July 2017

the accuracy of the content of MACS Service Reports. MACS, however, will
not be responsible for the accuracy of the information published nor will MACS
Worldwide be liable in any way for injury, labor, parts or other expenses resulting
from the use of information appearing in MACS Service Reports.

MACS Service Reports

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