ACtion Magazine - July/August 2017 - 14
As the blade turns
By Chris Tyson, MACS Heavy Duty Contributor
E
ngine cooling fans have one of the toughest jobs to do under the
hood of any vehicle, especially during these hot summer days
when temperatures can climb up to the 90s and beyond. Add to the
mix a long hill climb, or stop and go city driving, and you better hope your
cooling fan is up to the task, or it can leave you and the vehicle stranded.
We recently replaced an inop electric cooling fan on an older work
truck with one of those universal fit aftermarket fan kits. Most of the replacement job went smoothly enough: removing the old fan and associated wiring, fan shroud and mounting brackets. The new kit came with
everything we needed for a successful install. The technician also took
the time to do a pretty good splicing job on the new fan's power wires. He
studied the vehicle's wiring diagram and figured out the function of each
wire to ensure the fan would work.
Once the repair was complete, an idle test outside of the shop showed
that the fan turned on and off at the right temperatures, and the original
overheating problem appeared to be fixed.
But by the end of business the following day, that same truck was
back in our shop with the operator explaining that, while the engine does
run cooler, the temperature gauge is still too hot on the highway, and way
too hot in local traffic. That didn't seem to make sense to us, since we really went over the job with two sets of eyes and a fine-tooth comb, making
sure all the work was done correctly.
14
ACTION * July/August 2017
The operator then said something that simultaneously puzzled us and explained what was going on. His words went something like, "Oh yeah, one more thing. I walked around the truck
today, and it feels like hot air is blowing out of the front of the
vehicle. I never noticed that before. Is it supposed to do that?
Sure enough, that engine cooling fan was indeed spinning
backwards, blowing air in the wrong direction (from inside the
engine compartment out towards the front of the vehicle). It was
one of those things that we never even thought to check before
it left our shop, even though it's such a simple, easy test to perform.
In the end, the fix was quite simple: switching those two
power wires changes polarity to the motor (and the direction of
fan rotation), so it only took a few minutes to repair. This also
solved the slight overheat condition, too. When the fan was running backwards, it fought against ram air (a battle it just can't
win), and at lower speeds it wasn't properly flowing air under
the hood. Luckily this was an easy lesson to learn, and something each one of us should tuck under our hats. Just like those
two-speed fans (where we need to verify that both speeds work
properly), we also need to verify that air is flowing in the right
direction. ❆
http://www.lilandglobal.com/
Table of Contents for the Digital Edition of ACtion Magazine - July/August 2017
Outlook
Service Port
Leonard's Law
Virtual View
Cooling Corner
HD and OTR vehicle Service: Keep it Clean
Positive Pressure dor operator cabins
Industry News
Association News
New Products and Services
Last Watch
ACtion Magazine - July/August 2017 - Cover1
ACtion Magazine - July/August 2017 - Cover2
ACtion Magazine - July/August 2017 - 3
ACtion Magazine - July/August 2017 - 4
ACtion Magazine - July/August 2017 - 5
ACtion Magazine - July/August 2017 - Outlook
ACtion Magazine - July/August 2017 - 7
ACtion Magazine - July/August 2017 - Service Port
ACtion Magazine - July/August 2017 - 9
ACtion Magazine - July/August 2017 - Leonard's Law
ACtion Magazine - July/August 2017 - 11
ACtion Magazine - July/August 2017 - Virtual View
ACtion Magazine - July/August 2017 - 13
ACtion Magazine - July/August 2017 - Cooling Corner
ACtion Magazine - July/August 2017 - 15
ACtion Magazine - July/August 2017 - HD and OTR vehicle Service: Keep it Clean
ACtion Magazine - July/August 2017 - 17
ACtion Magazine - July/August 2017 - 18
ACtion Magazine - July/August 2017 - 19
ACtion Magazine - July/August 2017 - 20
ACtion Magazine - July/August 2017 - 21
ACtion Magazine - July/August 2017 - 22
ACtion Magazine - July/August 2017 - 23
ACtion Magazine - July/August 2017 - Positive Pressure dor operator cabins
ACtion Magazine - July/August 2017 - 25
ACtion Magazine - July/August 2017 - 26
ACtion Magazine - July/August 2017 - 27
ACtion Magazine - July/August 2017 - Industry News
ACtion Magazine - July/August 2017 - 29
ACtion Magazine - July/August 2017 - 30
ACtion Magazine - July/August 2017 - 31
ACtion Magazine - July/August 2017 - 32
ACtion Magazine - July/August 2017 - Association News
ACtion Magazine - July/August 2017 - 34
ACtion Magazine - July/August 2017 - New Products and Services
ACtion Magazine - July/August 2017 - 36
ACtion Magazine - July/August 2017 - 37
ACtion Magazine - July/August 2017 - Last Watch
ACtion Magazine - July/August 2017 - Cover3
ACtion Magazine - July/August 2017 - Cover4
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