Date: Thu, 13 Jun 2013 15:24:05 -0400
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: Dometic-Condenser fan running!
In-Reply-To: <1371146745.73554.YahooMailClassic@web121703.mail.ne1.yahoo .com>
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At 02:05 PM 6/13/2013, Robert Keezer wrote:
>Here's a tip for those servicing the fridge: Replace the factory fan
>with a computer fan. They are brushless type, use less amperage and
>are quieter. Lube the computer fan bearing with light machine oil
>before installing. Peel back the label and put one drop, then seal
>it over with the label. Use a small amount of thermal transfer
>compound like the type used for computers between the thermal switch
>and the fins. Robert 1982 Westfalia
Hi Robert,
I agree with the oiling technique, great way to get more life out of
a fan that's gotten sloppy. I think using compound under the
thermostat button is overkill, but there's certainly no harm in
it. But emphasis on very small amount, as the paste itself is a
lousy conductor and should be in an almost invisible film to fill in
molecule-size gaps in the contact face. Any more and it starts
working against you.
On the fans, though, I have to disagree. Typical box fans draw more
current**, move less air and make a nasty whining noise because of
their small high-speed blades. They're also inefficient in air
moving because of the small blades, which is why they have to spin so
fast. They *can* be very quiet but only at the expense of moving
very little air
The OE fan draws 50 mA, has a big slow-turning blade that moves a lot
of air quietly, and if you can more than just barely detect it it's
because the commutator has worn out and gotten noisy. The
Fridgemate/Valterra fan designed for the purpose is IMO a superior
replacement with an even larger blade (be sure the insulation clears
it) and similar 50 mA draw. Here's a drawing how to modify the stock
bracket to fit it: http://pws.prserv.net/synergy/Vanagon/Fan_bracket.gif
**I've never seen a box fan more than an inch in diameter that drew
less than 50 mA, and only one that drew that little. Even the ones
the size of a quarter typically draw 80 mA and move almost zero
air. I've got box fans here ranging from 20 mm up through eight
inches, including ones that draw a quarter amp or more at 110
VAC. I've got a 3 1/2" 12V fan that draws almost three amps and you
can feel the thrust when you hold it, and a 40 mm one almost 30 mm
thick that spins at close to 20,000 rpm and has fixed blades for the
airflow to bounce off. I've been in love with box fans since Rotron
invented them and called them Muffin Fans. But I've never seen one
that I thought was a really good replacement for the fridge fan. So
sitting on my pile of oh say a hundred various box fans I still paid
$25 for a FridgeMate fan to fix my Westy. Box fans are by nature
noisy pressure drivers, and what the fridge wants is a quiet volume driver.
Yours,
David
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