[DeTomaso] Blower mystery

David D Fisher fisher95020 at yahoo.com
Mon Aug 13 18:11:53 EDT 2012


    
Thanks Tomas,
 
The wiki animation is in line with my thinking.       In the pics that I show,  the motor is turning clockwise (looking into the picture).  Note that I have flipped the fans already before I took these pics.   
 
David
________________________________

From: Tomas Gunnarsson <guson at home.se>
To: David D Fisher <fisher95020 at yahoo.com>; Pantera mailing list <detomaso at realbig.com> 
Sent: Monday, August 13, 2012 1:50 PM
Subject: RE: [DeTomaso] Blower mystery


I forgot, vane curvature varies based on what you're trying to achieve. The
counterintuitive is sometimes more desirable. It's explained in this article
a bit down.

http://en.wikipedia.org/wiki/Centrifugal_fan

What's always important is the direction of rotation.

Tomas

-----Original Message-----
From: detomaso-bounces at realbig.com
[mailto:detomaso-bounces at realbig.com]On Behalf Of David D Fisher
Sent: den 13 augusti 2012 21:18
To: Pantera mailing list
Subject: [DeTomaso] Blower mystery


I have to start by saying that I wouldn't have believed this if I wasn't
seeing it first hand...

My car came with the heater disconnected and the A/C leaking so I decided to
pull the heater box apart and check everything before hooking back up.  I
had two ruptured coils (frost bite, I suppose), but that's a different
story...

When testing the fan, I noted that the fan blades appear to be oriented
backwards compared to direction the motor is spinning them.  I turn the fan
on and it moves a lot of air around the shrouds, but hardly anything moves
up through the heater box.   ( Note that the motor only goes one direction,
regardless off which polarity you wire it and it is turning in the direction
that the arrow stamped on the housing says it should. )

Upon further inspection of the fans I note there is an arrow also stamped on
them but it is pointing in the wrong direction compared to how the blade is
designed.   (enlarge the second picture to full size to see the arrow, and
the first picture to see the fan blade pitch)
http://poca.com/index.php/gallery/?g2_itemId=36973


Whoever assembled this in the factory did indeed match up the arrows from
the fan blades to the arrow from the motor as expected, but the design
appears wrong.   I took the fans off the shaft and flipped them over so that
they scoop air from the center and throw it out to the shroud.   Walla! 
lots of air moving through the box now!

Admittedly, this is still not quite correct as the shroud is somewhat like a
turbo housing and airflow is going in the wrong direction for the shroud,
but at least the fan is sucking in from the sides  pushing it into the
shrouds.

So, here is the mystery.   Is it possible that someone at DeTomaso purchased
the wrong direction fans from the supplier and an unwitting worker installed
them according to the arrows and a number of Panteras out there have heater
boxes that barely work on anything more than radiant heat?   Seems very
strange indeed.


David         
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