Jay, you are mostly right.
If you have it switched to 12v DC AND the engine is running AND the propane is
lit then you have BOTH heating the refrigerant which is a BAD practice. This is
also a problem with the 120v AC and propane combo. I have done this by accident
and I would not recommend it.
-Larry

Jay L Snyder wrote:

> I noticed last weekend while camping the fridge switch got moved to the 12V
> DC position.  The propane continued to run, so I am assuming this is switch
> only turns on 12V or 120V, with the middle position doing nothing to the
> gas side.  Would the switch being on the 12V position draw any extra
> current?  I was almost not able to start the engine the next morning, but I
> wrote it off as a weak starter.  (See previous post.)
>                                                         Jay