ACtion Magazine - January/February 2015 - (Page 8)
K.I.S.S.
Steve Schaeber
I
t's one of those basic acronyms we
learned in tech school: Keep It Super
Simple. You may have learned slightly
different terms, but the idea remains the
same, and refers to something known as
Occam's razor. Devised by William of
Ockham in the 14th century, the principle
says that when considering competing hypotheses, the one with the fewest assumptions should be selected. In other words,
all things being equal, the simplest solution tends to be the right one.
Reader Reply
8
ACTION * January/February 2015
Usually when tackling an HVAC performance problem, the first things technicians go after are the big ticket items:
compressor operation, radiator / condenser
issues, heater core / evaporator condition,
control panel function, blower fan output,
etc. Rarely are cabin seals thought of as
a primary suspect. But really, what we're
trying to do with an HVAC system is heat
or cool a certain volume of air. If that
amount of air is increased or decreased,
system performance will be affected. Mobile HVAC systems are designed according to cabin size, so consider this: can a
heater be effective if a door is left open?
Lately I've come across a few seal issues that have taken their toll on system
performance. If you check out the MACS
Blog at macsworldwide.wordpress.com,
you'll find a post from Chris Tyson where
he repairs a backhoe door seal at R&S
General Contractors. He explains that he
first suspected a system problem, such as
a clogged heater core, causing poor performance during engine idle. However, it
turns out that deteriorated door seals allowed so much cold air in that the heater
was not able to keep up.
My neighbor Mike has three Chevy
Astro vans, which have a doghouse engine
cover in between the front driver and passenger seats. Where this cover mates up
to the firewall, there is a foam rubber seal
around the edge. Mike explained the heat
in his 2001 van had not really been that
great. So, he took the van to his regular
shop, which concluded the blower fan was
not spinning fast enough. After an unnecessary motor replacement, the heater was
still not up to snuff, so the technician dug
deeper and found that the cover and seal
had been misaligned, creating an open gap
through which air could escape.
Seals are so simple, they are often
overlooked. But just like we seal the doors
and windows of our homes, we should
consider the important role they play in
mobile systems as well. ❆
Steve Schaeber
Manager of Service Training
You can reach Steve at
Steve@macsw.org
http://www.busacparts.com
http://macsworldwide.wordpress.com
http://www.macsw.org/imis15/MACS/Publications/ACtion_Reader_Reply/MACS/Publications/ACTION/ACtion_Reader_Reply.aspx?hkey=ac24bddb-c045-442a-813c-cbf05f88ac4d
Table of Contents for the Digital Edition of ACtion Magazine - January/February 2015
Outlook
Service Port
Leonard's Law
Member Profile
Compressor clutches
Recognizing career achievement
Virtual View
Heavy duty and off road
Industry News
Association News
New Products
Last Watch
ACtion Magazine - January/February 2015
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