Norcold fridge backup operation

The fridge is not in a slide. It does not currently have a fan in the chimney area or if it does I am not able to see it or any wires that might connect to it. I am contemplating installing a pair of 120mm, 72cfm, 17dBa fans but I want to eliminate all other possibilities before that so I won't feel like I wasted money on them if it doesn't get better. I was advised to unplug the thermistor and that would put it in full on mode which is where it has been for several days. The temp readings I am getting are a result of that and are about 2* cooler than when it was connected, so I don't think that it is bad. If I follow the suggestion about the temp button it shows the normal procedure and shows #9 where I have it currently set.
When I get the fans I will remove the unit to install them and verify the condition of the insulation around it as it may be less than needed as we all know the factory doesn't overdo anything. This coach had the first 2 owners in Texas, verified through documents and service invoices that came with it, so I have to believe it must have worked better than it does now.
Is there a preferred way to install the fans? I have seen mounted on the cooling unit, mounted to the back of the fridge midway up and in the roof vent under the cover. Which way is the most efficient to get max cooling effect?