Yep, that is the key question.

Measure it first with engine running and fridge turned off of 12v mode.
Then turn on 12v mode on the fridge switch panel and see what happens to
the voltage.

If a GoWesty aux battery relay kit is installed then this kind of issue
seems to be common. Sadly.

Mark

Vanagon wrote:
> What do you see for a voltage on the house battery with the engine running and the reefer turned on and set to the 12vdc mode?
>
>