Date:         Mon, 18 Sep 2000 15:30:24 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: Fridge Problem -additional coil fan
Comments: To: "Roy O." <keepsake@PANGEA.CA>
In-Reply-To:  <000901c0147b$b6347d00$e1580440@Pangea.ca>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 21:17 9/1/2000, Roy O. wrote:
>Earlier this summer I added a second coil fan in parallel with the stock
>fridge
>coil fan. It seemed easy enough to do (a real no-brainer) but now when the
>fridge is operating on propane, the flame indicator light on the cabinet
>control
>panel turns off whenever the fans are operating and lights up again when the
>fans stop.  Can anyone explain the connection between the fans and the fridge
>indicator light?

Roy, the thermocouple indicator works on a very small negative voltage (say
ten millivolts) developed between the two sides of the thermocouple.  The
body of the gas valve is essentially the ground reference here, and if the
LED panel used that for a ground you'd probably not see such
variations.  However the LED panel uses a ground wire attached elsewhere --
I forget just where -- and current passing through this ground path causes
it to change voltage slightly compared to the gas valve.  It's only
slightly, but again we're working with tiny voltages.  You can improve the
ground, specifically tying it to the gas valve, and/or you can increase the
gain of the LED amplifier (see schematic on my website) which will give you
more control over when and how much the pilot LED lights.

david
David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"