Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. Today he discusses an RV refrigerator that freezes the food.
I have a 2020 Fox Mountain by Northwood. The fridge in this rig is a Norcold N10LX. Today the fridge was so cold on its lowest setting the eggs froze and split. I called the dealer. The dealer questioned me on the placement of the thermistor on the fins above the moisture pickup tray. The thermistor had never been moved from the 10th fin from the right and was making proper contact with no corrosion. He suggested I move it to the 5th fin from the right side. Does this really make any difference? Would it make more sense that the thermistor might be faulty? I did have to replace the thermistor in our previous trailer’s fridge after one year. Any other suggestions or tips? Thanks. —Andrew
Typically we don’t get questions about the absorption refrigerators being too cold. Usually they’re not cold enough! There are a few things that could cause this situation and, yes, the placement of the thermistor or temperature sensor could be one of them.
The first thing you always want to check with any appliance that operates on dual power modes such as your refrigerator is does this happen on both modes, 120 volt and LP? This will isolate the issue to either the power source or a component. My guess is that it probably does.
So let’s take a look at the thermistor, which is the temperature sensor that is attached to your evaporator fins inside the refrigerator compartment.
Inside your refrigerator there are several what I call temperature “pockets” if you do not have a circulation fan on the bottom shelf. As warm air rises, it can get trapped at the top of your refrigerator compartment. If your thermistor is in the middle of the fins and up to the top, it will sense a warm air pocket and keep the refrigerator running all the time. It is best to move the thermistor to the right side and lower it to about 1/2 or lower. The label in the photo above actually states that.
It is easy to test the thermistor by removing it from the evaporator fin and placing it in a glass of ice water. This will get it down to almost 32 degrees and then you can test it with a multimeter. There should be an automotive style plug in to remove the probe and test the ends. Set your multimeter to ohms or resistance. Here are the values from the Norcold N10LX Service Manual.
You will need to check the temperature of the water, as well, to get the right value.
If your thermistor is good, then I would suggest checking the gasket of the door. It could be letting warm moist air inside and throwing the temperature off, and freezing things as well. It’s not uncommon for the door to sag with heavy items placed inside and bouncing down the road. I won’t say how fast, as I seem to get in trouble with that! Place a dollar bill between the door and the frame and shut the door. The dollar should have a slight tug when pulling, then you know it is sealing. Do this all around the door.
Also, check the control panel to make sure there are no error codes. If all these are working, it must be poor air circulation. That could also be caused by blocking the shelves with aluminum foil or plastic. Get a small 9-volt circulation fan and let us know the results.
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We have a small gas absorption refrigerator in our 21′ Coleman. We keep track of the temperature on the lower shelf with a remote thermometer since it can reach freezing temperatures very easily under normal outdoor temperatures. We set the temperature control up or down as needed based on what the thermometer is telling us. We try to keep the temperature on the lower shelf between 36 and 40 degrees. Usually works pretty well for us.