ACTION NAPA AUTO CARE - 5

By Steve Schaeber, MACS Technical Editor

A

MACS

utomotive engine cooling systems have relied
on a fan of some type and in some conﬁguration on most vehicles. Traditionally this fan
had been a mechanical type device, usually
operated directly by an engine driven belt off
of the crank shaft pulley. Since the explosion in popularity of
transverse mounted engines in the late 1970s however, electric fans have become the norm and are certainly the most
popular way to cool an engine today.
Mechanical fans work great, and while their numbers are
relatively small, they are still used in a wide variety of vehicles, especially trucks. They are belt driven off the engine
crank pulley, and typically use either a thermostatic clutch or
pneumatic fan drive. Probably their biggest drawback is that
no matter how they are controlled, because they are physically connected to the rotating engine pulleys, there is no
time when they can be completely turned off. Even when
their clutch is disengaged and they are running in "free wheel
mode," their components are still a drag on the engine. This
constant load, while small and seemingly insigniﬁcant, does
have an effect on an engine's overall efﬁciency.

MACS

MACS

A belt driven fan with thermostatic clutch on a Chevy
Suburban.

Atypical of most vehicle designs, the Jeep Cherokee
had long used a mechanical fan for primary engine
cooling with an electrical fan as a back-up for extreme temperatures. On models equipped with A/C,
the electric fan is commanded on along with the
compressor clutch.

Spring 2015 * ACTION/NAPA

5

ACTION NAPA AUTO CARE

Table of Contents for the Digital Edition of ACTION NAPA AUTO CARE

ACTION NAPA AUTO CARE - Cover1
ACTION NAPA AUTO CARE - Cover2
ACTION NAPA AUTO CARE - 3
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ACTION NAPA AUTO CARE - Cover3
ACTION NAPA AUTO CARE - Cover4
https://www.nxtbook.com/nxtbooks/macs/action_20170708
https://www.nxtbook.com/nxtbooks/macs/action_20176
https://www.nxtbook.com/nxtbooks/macs/action_201706
https://www.nxtbook.com/nxtbooks/macs/action_201705
https://www.nxtbook.com/nxtbooks/macs/action_201704
https://www.nxtbook.com/nxtbooks/macs/action_201703
https://www.nxtbook.com/nxtbooks/macs/action_20170102
https://www.nxtbook.com/nxtbooks/macs/action_20161112
https://www.nxtbook.com/nxtbooks/macs/action_20160910_v2
https://www.nxtbook.com/nxtbooks/macs/action_20160910
https://www.nxtbook.com/nxtbooks/macs/action_20160708
https://www.nxtbook.com/nxtbooks/macs/action_napa_2016spring
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https://www.nxtbook.com/nxtbooks/macs/action_201604
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https://www.nxtbook.com/nxtbooks/macs/action_20151112
https://www.nxtbook.com/nxtbooks/macs/action_20150910
https://www.nxtbook.com/nxtbooks/macs/action_20150708
https://www.nxtbook.com/nxtbooks/macs/action_napa_2015spring
https://www.nxtbook.com/nxtbooks/macs/action_napa_2015spring_v2
https://www.nxtbook.com/nxtbooks/macs/action_201506
https://www.nxtbook.com/nxtbooks/macs/action_201505
https://www.nxtbook.com/nxtbooks/macs/action_201504
https://www.nxtbook.com/nxtbooks/macs/action_201503
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https://www.nxtbook.com/nxtbooks/macs/action_20141112
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https://www.nxtbook.com/nxtbooks/macs/action_20140708
https://www.nxtbook.com/nxtbooks/macs/action_201406
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https://www.nxtbook.com/nxtbooks/macs/action_201404
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https://www.nxtbook.com/nxtbooks/macs/action_20140102
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https://www.nxtbook.com/nxtbooks/macs/action_20130910
https://www.nxtbook.com/nxtbooks/macs/action_201307
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https://www.nxtbook.com/nxtbooks/macs/action_20121112
https://www.nxtbook.com/nxtbooks/macs/action_20120910
https://www.nxtbook.com/nxtbooks/macs/action_201207
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https://www.nxtbook.com/nxtbooks/macs/action_20120102
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