Here is a link for the operation and maintenance of this unit. As these
small ridges are designed to operate with very little or in many cases with
no electrical power at all the push button controls do not control the
propane operation. The only thing pushing the "gas" button does is turn off
the 12V and 120V operation and turn on that gas re-igniter circuit. After
the flame is lighted it is possible to turn on one of the other sources  and
actually have two sources working at once. This can cause overheating of the
coolant system and damage the fridge. So yes whenever you wish to switch off
of gas the gas valve has to be closed.

http://www.thetford.com/HOME/PARTS/NorcoldIncRefrigerators/GasElectricRefrig
erators/3163Series/tabid/471/Default.aspx

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Carlos & Margaret de Carvalho
Sent: Wednesday, April 25, 2012 2:46 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Fridge

I have a problem with my Norcold Model 3163 refrigerator in my V.W. camper
van.
The fridge lights and runs well on all three settings.AC,DC & Gas but when I
press the gas off switch it keeps on burning. The only way I can switch off
is to shut the main gas valve at the tank Can anyone help.

Carlos.