Date:         Tue, 27 Sep 2005 00:17:14 -0400
Reply-To:     Dennis <guskersthecat@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Dennis <guskersthecat@YAHOO.COM>
Subject:      Dometic Fridge Electronic Ignition not working - resolved

The original problem posed in this thread was my fridge LED, turning on,
but not blinking, and no audible spark igniting the propane burner.

I just finished pulling/replacing the fridge and here are my
comments/methodology:

1.  Pulling the fridge is a pretty simple job.

2.  For a 15 year old van, there was surprisingly little crap on the
diffusers or behind the fridge.

3.  Pulling the insulation behind, there was definite surface rust along
the lower and rear seams.  I cleaned these up as best I could and sprayed
the entire panel with Rust Check, a liquid rust treatment similar to Krown.

4.  After cleaning the combustion chamber, orifices, spark unit, setting
the spark unit gap, and blasting everything with 120 PSI air, I reconnected
the fridge in the van.  The problem was not resolved.

5.  Checking voltages at the van side of the fridge's wiring harness, I had
13.5 volts on two of the leads (with the van off) and a good ground,
showing zero resistance to the negative battery terminal.

6.  Putting the fridge back on my bench, I figured the spark unit itself
might be at fault.  I pulled the positive wire off the terminal at the
propane push switch,  leaving it connected to the spark unit. I also pulled
the black (control?) wire to the LED from the spark unit.  When applying 12
volts (from a 6 amp battery charger) to the postive wire and grounding to
the spark unit negative terminal, suddenly it was sparking like mad.

7.  Tracing the power path back to the wiring harness, it was clear that
all the connections were good.  Plugging the fridge harness back into the
van, it was now working perfectly.  Once the dometic was reinstalled, the
unit fired right up.

None of the connections seemed corroded, and all the connectors looked
good.  So other than reseating the spark units terminals, I really did
nothing...and I have no idea why it's working now.  It was either a flaky
spark unit (we'll have to wait and see) or a simple connection issue.

What is also not apparent is how the spark unit senses flame and stops
sending voltage.  The spark unit has constant power, ground and one control
wire to the LED.  The LED's other lead goes to ground.  Anyone know how the
spark unit is stopped when the burner is lit?