MACS Service Reports - 2015 - AUG1

Total Vehicle Climate and Thermal ManagementTM

August 2015

By Dave Hobbs, MACS Field Correspondent

Summer can be hot and vacations can be pricey. A combina- entire vehicle and this includes the HVAC system. The number
tion like that typically leads to concerns for the best comfort pos- of methods currently in use by OEM engineers to meet increassible from a vehicle's HVAC system, along with fuel economy ing government mandated CAFE (Corporate Average Fuel
to help maximize your customers' travel budgets. This MACS Economy) standards total around two dozen. Changing the
Service Report will help you understand the designs and service way A/C compressors operate is one of them. See Figure 1.
diagnostics of the latest A/C
compressors. We'll focus
on belt driven conventional
compressor changes related
to fuel economy in order for
you to help your customers
go further and stay cooler,
wherever their summer travels take them.
Who
would
have
dreamed 10 years ago that a
new Ford F-150 truck would
have extensive aluminum
body construction? Vehicle
weight reduction technologies such as carbon fiber,
once considered too expensive for production vehicles,
are making their way into
the family car too. Carbon
Fiber Reinforced Plastics
(CFRPs) are predicted to
gain widespread adoption
for automotive lightweighting by 2025, one industry
study group has concluded Figure 1: Of the energy within a gallon of gasoline, only around 20% actually gets to the wheels to propel the vehicle
city driving conditions. While that number goes up closer to 30% for highway driving, it's not a good statistic.
recently. In the world of fuel under
Heat losses within the engine are the biggest wasters of this energy and the toughest challenge. Those parasitic losses
economy, light is right for the such as turning water pumps, alternators and A/C compressors aren't huge, but do add up.

ALSO INSIDE THIS ISSUE:
Understanding and Diagnosing the DCV ................................................................................................................................... 3
Increasing MPG by Keeping A/C from Getting TOO Cold!....................................................................................................... 5
Externally Controlled Variable Displacement Compressors (eVDC) .................................................................................... 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

August 2015

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

US Department of Energy

COMPRESSOR VARIABLES THAT KEEP CUSTOMERS COOL AND SAVE FUEL

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