MACS Monthly Newsletter - 2021 - JUN1

Service Reports
MOBILE AIR CLIMATE SYSTEMS ASSOCIATION ©

By Paul Weissler, MACS Senior Technical Correspondent

June 2021

" Water " Cooling Comes to A/C
an auxiliary system, with its own radiator, running at comparatively low temperature, to perform any or all of these
supplementary functions.
Even if you don't service the larger trucks, you may have
worked on some diesel engines or surely turbocharged
gasoline engines and/or gasoline-electric hybrids with
auxiliary, low-temperature cooling. As soon as you lift the
hood, the additional coolant reservoir (or even two additional reservoirs) is the immediate tipoff (Figure 1).
Tying the air conditioning system into the water cooling
system for a high-voltage battery pack is another, somewhat less-familiar circuit, but it actually dates back over
10 years to the Chevy Volt. Now there's still another A/Crelated function appearing on European cars: using a
low-temperature water-cooling system for the condenser.
It's shown up on some BMWs and now it's being used on
what is ostensibly an American car, the Jeep Renegade

Paul Weissler

techauthority.com

Low temperature cooling systems are hardly new, but
they're increasing in number, and the reasons are simple: gasoline or diesel engines are increasingly being
turbocharged (or a few, supercharged), and many of the
charge air coolers are using water cooling (well, waterantifreeze solution) for increased efficiency. Additionally,
hybrids and battery electric vehicles are an increasing
part of the market, and they often use water cooling for
the power electronics, and in some cases (in conjunction
with the air conditioning system) for the high-voltage battery packs. As should be obvious, these additional water
cooling functions can't tap into the engine cooling system
because it runs at higher temperatures. So, the car gets

Figure 1: This Chrysler Pacifica plug-in hybrid has three
coolant reservoirs (and separate coolant circuits) for the
engine, battery pack and power electronics. The latter
two are low-temperature circuits.

Figure 2: Water-cooled condenser (2) is mounted in the powertrain compartment as shown. Other parts are (1) refrigerant
lines block, and (3) receiver-dryer.

ALSO INSIDE THIS ISSUE:
Humidity Sensors For A/C, Defrost Control...............................................................................................................................2
That Flow Sensor In Toyota And Lexus Vehicles .................................................................................................................. 5
Things That Happen To Old Cars ....................................................................................................................................................... 6
MACS Service Reports is the official technical publication of the
Mobile Air Climate Systems Association, 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

June 2021

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 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

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MACS Monthly Newsletter - 2021

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