Date:         Sun, 5 Apr 1998 09:15:57 8
Reply-To:     Wes Neuenschwander <wesn@ESKIMO.COM>
Sender:       Vanagon Mailing List <Vanagon@vanagon.com>
Comments:     Authenticated sender is <wesn@mail.eskimo.com>
From:         Wes Neuenschwander <wesn@ESKIMO.COM>
Subject:      Re: Dometic Fridge Lighting Problems
Comments: To: vanagon@vanagon.com

> Date:          Thu, 2 Apr 1998 08:37:56 -0500
> From:          Morris Arthur <morris@CMR.SPH.UNC.EDU>
> Subject:       Dometic Fridge Lighting Problems

> Here's my situation:
>
> I open the valve, hold in the override button, pump air through the
> combustion chamber, and spark: nothing.
>
> *But*, if the fridge is running on AC and I immediately follow with the
> above procedure, the burner gets lit....
>
> Could my override button be non-functioning such that gas only flows when
> everything's hot ? Other suggestions ? I'm baffled...
>
> Morris
> '83.5 Camper
>

I think it's unlikely that the 'override' button is the problem.  When you
depress button it pushes a small stop away from the gas valve seat,
allowing gas to flow to the burner.  Heat from the ignited burner generates
a *very* small electric current which energizes a *very* small magnetic
coil, retaining the stopper when the button is released.  So if this valve
is bunged up, the typical result is that the burner won't light, period
(i.e., pushing the button generates *way* more force than the coil ever
could).

Much more likely, I think, is a dirty burner and/or flue pipes.  When
these get dirty (which they do, regularly), air-flow is impeded, making
combustion difficult.  Actually, combustion in these things is difficult
enough even when they're clean, relying on siphoning fresh air down one
tube and venting combustion gases up another.  The function of the air pump
is to provide enough fresh air to start the burner which then establishes
an induced airflow via the "stack-effect" (hot gases rising through the
exhaust flue).  This stack effect basically is what starts the siphon.  The
reason you're able to light the burner after you've been running on 120VAC
is that the electric heating element heats the exhaust flue somewhat,
creating a stack effect and inducing some air-flow in the flue.

My recommendation is that you pull the refer and clean the burner and flue
assembly.  You might also want to re-build the air pump (the O-ring may be
leaking, making the pump ineffective), performing the pump modification if
it hasn't been done already (consists of drilling out the air discharge
port to allow more air-flow).

-Wes


Wes Neuenschwander
Seattle, WA
wesn@eskimo.com