MACS Service Reports - 2016 - FEB8

HOW MUCH OIL SHOULD THE SYSTEM HAVE?

Paul Weissler

Most veteran HVAC technicians can remember
when 10-11 ounces was the standard A/C refrigeration system oil fill, even for a front only system.
Then we saw it gradually drop to the 7-8 ounce
range. But the need to reduce A/C fuel consumption
has become of increasing importance, and compressors have been reengineered to incorporate an oil
separator to significantly reduce the amount of oil
circulated with the refrigerant. Although it might
not seem like a lot, it does take compressor power

Figure 10: Oil fills are coming down. As this Ford F-150 label says, the system contains 100 cc or 3.4 oz of PAG oil.

to circulate oil with the refrigerant, and the power
saving from reducing the quantity is measurable,
and contributes to A/C related fuel efficiency.
Because most of the oil is now being retained in
the compressor, there's obviously less need for oil
droplets flowing with the refrigerant to perform
compressor lubrication. That's been the reason why
the oil fill amount is being reduced. And we expect
to see changes in the way systems are put back into
service when a compressor is replaced, perhaps
eliminating the addition of oil to the evaporator
and condenser.
So where are we headed? We've been seeing systems with 100 cc, either on the compressor and/or
an underhood label. For the metrically challenged,
that's 3.4 ounces, and the latest vehicle we've seen
it on is the new Ford F-150 (Figure 10).
A logical question that's been raised for the last
several years: will this reduction in oil circulation
affect the ability of trace dyes to indicate leaks?
After all, the dye mixes with the oil, and it's only
when a dyed droplet of oil escapes from a leak that
there is a visual indication of a leak. The answer
seems to be that there will still be enough oil kept
in circulation for the trace dyes to work. And with a
number of car makers installing trace dye on the assembly line (and/or recommending its use for leak
detection), there's no reason to suspect that trace
dye is going away. ■

MACS 2017
MACS has big plans for 2017
In 2017, the MACS Training
Event and Trade Show will take place
at the Marriott hotel in Anaheim, CA,
February 15 to 18.

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.

February 2016

MACS Service Reports

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