MACS Monthly Newsletter - 2021 - APR3

Mike Bailey

Figure 6: Automotive scroll compressors also rely on refrigerant
to supply needed oil.

Mike Bailey

Figure 4: York and Tecumseh
used " dip and splash " to lubricate the rotating and reciprocating parts. These were used
in older light duty and heavyduty applications until recently.

incorporated an oil pump
and sump into their design.
The York/Tecumseh design
in Figure 4 uses a dip-andsplash system to lubricate the
internal parts. The Frigidaire
A6 in Figure 5 and Chrysler V2
(not pictured) used gear-type
pumps to lubricate the internal parts. These compressors
could operate for a long time
without refrigerant in the system.
The lower compressor
shown in Figure 5 represents
a modern compressor. No oilpump. A swash plate or scroll
design, shown in Figures 6
and 7 require continuous, adequate refrigerant and therefore oil flow to survive in its
environment.

Figure 7: A swash plate allows for " fixed-displacement " , opposing cylinder operation.
another. Listed are a few more points to ponder before quoting the job, all in
one place. Some are personal preference.
* PERFORM A LEAK TEST... to avoid the failures mentioned earlier
in this article!
* IDENTIFY THE SYSTEM... to determine a course of action. Orifice
tube or TX valve? Where will the most compressor debris be deposited in the system?
* IDENTIFY COMPONENTS... is that a muffler or filter? Can it hold
debris? Can that debris be flushed out or should it be replaced?
* TAKE A HISTORY... has the system been serviced in the past?
* COMPONENT DESIGN... can I flush that condenser, or should it
be replaced? Is that a filter/dryer, an old school receiver/dryer or
just a filter?
* HOW DID THE COMPRESSOR FAIL...is it noisy or did it self-destruct during use, grind its internals to bits and deposit that debris
throughout the system?
* HOW MUCH OIL REMAINS...in the system?
* IS THE REMAINING OIL CONTAMINATED...with grindings and debris?

Figure 5: Old school Frigidaire A-6 compressor on top. That
" bump " in the compressor body (far right) is the oil pan
and the tube extending from the inner assembly is the oil
pickup. You can see the oil pump gears in the rear head
(far left). This compressor was noisy. You can see the oil
pump drive is broken off the rear of the swash shaft. Below
is a Ford FX10 compressor that is typical of most modern
swash-plate units. No oil reservoir or oil pump. It is fully
dependant on refrigerant to supply oil.
Famous quotes
This vehicle is in your bay, you have now diagnosed a failed compressor.
Many technicians will run with it and quote a compressor, flush and dryer.
Not so fast. Can we make sure we have all the bases covered before quoting
the job? We all agree that a complete inspection and diagnosis can minimize
warranty comebacks and can grow both sales and customer confidence.
Having to make a second (or third!) call to update an estimate is embarrassing and unprofessional.
Many of the following have been covered in this publication at one time or

April 2021

MACS Service Reports

MACS Monthly Newsletter - 2021

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