MACS Service Reports - 2015 - NOV3

NUTS AND BOLTS
A/C Preventative Maintenance - Refrigerant, Drier &
Compressor

The nuts and bolts of PM are what you most likely
began with as a new technician, regardless of when you
entered the workforce. A little has changed, of course, to
say the least. Let's throw out some of the most routine
items and then focus a bit harder at those related more
to HVAC.

Looking at the PM Truth Chart should trigger some
thinking outside the box (Figure 2). While it is true that
refrigerant doesn't grow mold from being in your customers' A/C systems too long, we must remember that:

A/C Preventative Maintenance - Clutches, Belts,
Hoses and Airflow

1. PAG oil is hygroscopic (absorbs moisture)
and systems do pull in air over time (slight
leakage) which means moisture accumulation.
2. Receiver/driers and accumulators do
contain this moisture, but have life spans requiring replacement. Desiccant isn't a forever
product.
3. During the early stages of system refrigerant losses due to slight leakage, the pressures
drop on the low side just enough to actually
provide lower duct outlet temps during low
heat load conditions. Customers often think
everything is great. However, this comes at a
price; lower refrigerant flow that results in less
lubrication which in turn causes higher compressor temperatures.
4. Overheated compressors cause overheated

Dave Hobbs

The MACS Wordpress Blog, regularly posted as emails to MACS members, has been honored as the best
B2B automotive aftermarket blog by the Automotive
Communications Awards for 2011, 2012 and 2013. As
a good review to the clutches, belts, hoses and airflow
side of A/C preventative maintenance, be sure to search
Google for MACS Worldwide 8 tips for A/C Preventative
Maintenance, and follow those somewhat obvious but
often overlooked tips for keeping your customer's A/C
system operating in tip top condition in order to reduce
the possibility of more expensive A/C repairs down the
road. Everything from looking out for those damaged /
missing air dams for bottom breathing cooling systems
to restricted condenser airflow to the neglected compressor drive belt is covered in that MACS blog.

Figure 2: This PM Truth Chart illustrates how some of the traditional thoughts on maintenance have changed.

November 2015

3

MACS Service Reports



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

MACS Service Reports - 2015 - JAN1
MACS Service Reports - 2015 - JAN2
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MACS Service Reports - 2015 - NOV1
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