My experience with the Fridge Defend has not been a positive one and I always level the rig. It may work fine on a Norcold or Dometic system but does work for me on a Dutch Aire cooling unit with a Norcold control board.
What we experienced with the Fridge defend is that when it is cutting on and off (I think it is about a 20 minute cycle) it did not maintain adequate cooling. As set by the manufacturer, it cycled on and off even when level and not moving.
I put in a Dutch Aire cooling unit and a Fridge Defend last year. The fridge works great as long as I don't turn on the Fridge Defend. When I do, it turns the system off and on causing the system to go above 45 degrees. I texted back and forth with the manufacturer/creator of the Fridge Defend and was told that the Dutch Aire does run at a higher temp than others. He didn't give me any info on what to put the settings on for the Dutch Aire unit. His final statement was that the cooling unit is bad.
While in my drive way and perfectly level, I was able to change some of the setting on the Fridge Defend and get it to run longer without cycling on and off. But when the truck is on the road it didn't work for me at all. I have to assume that it isn't compatible with the Dutch Aire.
Turning the Fridge Defend off, I have now run the fridge for months and it works great, better than the original Norcold. So for me, the Fridge Defend was a complete waste of money.
Again, it may work correctly on Norcold and Dometic systems.
