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<title>A lot more complicated Giammalvo</title>
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<center><big><big><b><i><font color="#3333ff">Giammalvo Files</font></i></b></big></big></center>
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<img src="mark3.jpg" alt="Mark Giammalvo"
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<p><i><font color="#000000">Mark Giammalvo specializes in driveability
diagnostics </font><font color="#000000">at his family business,
Sam Giammalvo's Auto Sales & Service, Inc. in New</font>
<font color="#000000">Bedford, MA. </font> </i>
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<i><font
color="#000000">Mark, who has been with the business for
over 20 years, is an ASE Master Technician and Parts Specialist.
He also holds the ASE L1 certification, and has an
associates degree in business</font> <font color="#000000">management.
<br>
Mark is also a writer for Motor Age Magazine and is the past secretary
of the Alliance of Automotive Service Professionals, (AASP).</font></i>
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<big><big><b> A Lot More Complicated</b></big></big>
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<p><small><i><font color="#000000">(Printed in the Journal of The Alliance
of Automotive Service Providers, AASP) </font></i></small></p>
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<p>Recently I read a Chrysler Technical Service Bulletin about "new
cooling fan strategy." After reading that bulletin, I was motivated to write
this article in an attempt to convey how complicated automotive technology
has become. </p>
<p>Traditionally cars were rear wheel drive, meaning that the engine
turned the rear wheels to power the vehicle. Back then, the engines were
mounted in the car "in line" with the drivetrain, meaning, from front to
back. The fan belts were on the front of the engine and the belts spun the
engine cooling fan, which cooled the coolant in the radiator. From the 1980's
and on, front wheel drive cars started to dominate the marketplace. On front
wheel drive cars, the engine is mounted transversely, meaning that the engine
is mounted "sideways" under the hood. Due to this configuration, the drive
belts are now behind the right front or left front wheel and not anywhere
near the radiator. As a result, a belt driven engine cooling fan cannot be
used. Since then, front wheel drive cars have had electric fans mounted on
the radiator. The engine computer senses when the engine coolant is getting
hot, (about 225F), and powers on the cooling fan. When the coolant temperature
drops, the computer shuts the fan off. This cycle repeats itself as needed
while you are driving. Typically the fan never comes on above 30 MPH since
at those speeds there is sufficient airflow passing through the radiator,
so fan operation is not required. The fan will normally come on at low speed,
stop-and-go, or idle type driving. </p>
<p>Well, that old strategy just got a lot more complicated thanks to
Chrysler. Recently we came across Chrysler service bulletin # 07-003-01,
which explains new cooling fan operating characteristics on some of their
2001 model year vehicles. Now fan operation will also depend on windshield
wiper speed operation. What you ask, do the wipers have to do with the engine
cooling fan? Well I'll let you read it in their own words. The copy of the
bulletin follows: </p>
<p><i>"Owners may complain that the engine cooling fan runs constantly,
coming on just as the vehicle comes to a stop, or that the cooling fan
may be intermittently running under cool weather or cool engine conditions.
Technicians performing routine diagnostic procedures may notice that the
cooling fans are running under conditions that would not normally require
cooling fan operation.</i> </p>
<p><i>Just before the 2001 model year launched, a radiator steaming
condition (water vapor rising from the front grill opening) was detected
following a drive in the rain. The water vapor is a result of moisture (rain)
build up on the radiator under certain specific conditions and not the indication
of a vehicle overheat problem. To prevent owner concern over this water
vapor, the cooling fan strategy in the Powertrain Control Computer was revised
to command on the cooling fans under the following conditions:</i> </p>
<p><i>1. Ambient air temperature is greater than 25F.</i> <br>
<i>2. The engine coolant temperature is less than 195F.</i>
<br>
<i>3. Windshield wiper motor speed and vehicle speed is
above a certain threshold.</i> <br>
<i>4. Under these conditions the cooling fan will turn on
at vehicle speeds less than 20 MPH.</i> </p>
<p><i>This strategy will turn off if any one of the following conditions
are met:</i> </p>
<p><i>1. The vehicle must travel more than 100 miles without the
windshield wiper motor on.</i> <br>
<i>2. The engine coolant temperature drops below 100F. </i>
<br>
<i>3. There are 10 minutes of accumulated time with the
engine coolant above 220F."</i> </p>
<p>It's obvious that diagnosing the cooling fan circuit of these cars
is not going to be as easy as it used to. As these vehicles age and develop
problems, we will have to look at the wiper motor and vehicle speed sensor
as possible trouble when diagnosing the cooling fan circuit. Who would
have ever thought cars would have become this complicated? <br>
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