If you are wondering what makes your RV refrigerator freeze, then this article might save you a ton of pain (and maybe some money!)

Why Does My RV Refrigerator Freeze Everything?

While researching for another article on RV refrigerators recently, I came across a popular question that a LOT of people were searching for. I did a little digging later and it took me WAY too long to find the answer.

Now, this really bugged me- so I decided to create this resource for everyone.

The question was really simple- Why Does My RV Refrigerator Freeze Everything? Here’s what I found out:

The most common reason your RV refrigerator might be over-cooling is because the thermistor/ thermostat inside the fridge is either turned up too high or isn’t working properly. Another common reason is warm, humid air from outside entering the refrigerator through and frosting over.

Let’s look into what all this really means.

Firstly- What is a Thermistor or Thermostat?

Once you open your fridge and look towards the back side of the top shelf, you will see the metallic fins through which cold air comes in.

If you have a Norcold fridge, you will see a thin wire inside a white clip-on, attached onto one of the fins. This is the thermistor. In Dometic fridges, this clip-on is present at the side of the fins.

A thermistor gets its name because it is literally a temperature varying resistor. Simply put, in any circuit- with varying resistance, the voltage and current flow changes with changes in the refrigerator temperature. Using thermistors is a an easy way to measure temperature in an RV refrigerator electrically.

In the context of the RV fridge, the thermistor controls the amount of cooling generated inside the fridge by controlling the voltage and current – roughly speaking.

If the thermistor goes bust, then the refrigerator keeps continuously pushing cold air through the metallic fins at the back- which can lead to the fridge freezing everything.

Another reason for the temperature being too cold may also just be that the thermistor setting was accidentally turned to a colder level. This is sort of a “lens cap, lens cap, lens cap” problem (put a comment below if you want me to explain).

Many RV owners don’t even know about the temperature setting knob inside their fridges, which is why it doesn’t even strike them to regulate the temperature using it, and check if the setting was accidentally moved.

So, first things first, we’ll need to check that.

How to change the temperature setting in your RV fridge

• If you have a Dometic fridge, you’ll see the clip on the top right corner of the fridge, as you open it. The higher you drag it upwards, the lower the temperature will go. If you drag it downwards, the temperature will rise.
• If you have a Norcold fridge, you’ll see the clip-on attached to one of the metallic fins. You’ll need to drag the clip in a horizontal direction to manipulate the temperature, rather than vertical, as in the case of a Dometic fridge.
• All other RV fridge brands– you’re probably going to have a similar set-up for temperature control. If you’re not sure how to work the thermistor, or where it is, you can take a look at the user manual, or look it up online if you don’t have one.

Now that you know how the thermistor works and where it is- bring it to a moderate temperature setting, and leave the refrigerator be for the next 4 hours.

While the frost build-up wouldn’t have gone yet, you should see some improvement in the temperature inside the fridge.

If this doesn’t do anything, then the next thing to check is whether the thermistor is malfunctioning.

How to check for a malfunctioning thermistor

This is a simple test that ANYONE can perform really. You’ll need a multimeter and a glass of ice water for this.

If you’ve never used one before- a multimeter is used to test electric circuits. You can test a lot of things, such as the voltage, current, power consumption, etc.

However, we just need to test the resistance.The idea is to use the multimeter to measure the resistance of the thermistor and how it varies with temperature.

1. You’ll notice that the thermistor leads are attached in a harness above the top shelf of the fridge- where your lightbulb might also be hanging from.
2. If not so, the leads will be attached to a circuit at the back of the fridge, which you’ll have to access by removing the rear panel with a screwdriver.
3. You’ll need to remove the thermistor from the clip-on and also take out it’s leads which are plugged into the circuit.
4. Next, you’ll attach the multimeter probes to the two ends and put the multimeter setting to ‘Resistance’. If you’ve never used one before- it’ll probably be the setting with a ‘R’ written and an ‘Ohm’ symbol.
5. Note the resistance level being displayed on the multimeter
6. Now, put the thermistor in cold water and see if the resistance changes
7. If the thermistor is working fine, you’ll see an increase in resistance. If there is no change in resistance, it means the thermistor isn’t functioning properly and needs to be replaced.

Here’s a video demonstration of what I just described:

How to replace the thermistor in your RV refrigerator

You may want to get the Dometic thermistor replacement kit , OR, if you have a Norcold, then the relevant thermistor wire assembly for the Norcold Refrigerator . You could also go for just about any other thermistor as well, if you prefer- it’ll all work the same.

1. First, unplug the thermistor leads from the circuit.
2. Remove the clip-on to expose the thermistor inside.
3. Clip the thermistor off the wire
4. Trim back about ½” of the plastic coating using a wire stripper to expose both the positive and negative ends of the wiring
5. Attach your new thermistor to the wiring.
6. Plug the leads back into the circuit and you’re done!

Here’s a helpful video tutorial on how to replace your thermistor:

Gasket leak may also be causing frost which causes your RV refrigerator freeze

Okay, so you tested out the thermistor and that didn’t work. This means that you should now be checking for leaks in your refrigerator, where outside air could be coming in from.

What happens is this:

Relatively warm, humid air from the surroundings finds it’s way inside the fridge and meets the cold air inside. Upon coming in contact, the humidity in the outside air cools down and forms frost.

A good indicator of where the leak in your fridge could be- is where is the frosting occurring the most?

Is it by the doors? Top shelf? Lower shelf? Freezer?

To this end, the first thing that you should check is the fridge door gasket and whether it is sealing correctly. A simple way to do this is to stick a piece of paper between the refrigerator doors and close them.

If you’re able to move the paper around- you’ve found the issue! The gaskets aren’t sealing tightly enough and need to be replaced.

Repairing the leak also saves you money because your fridge will now be more efficient- meaning, it will use less power to provide the same level of cooling it had to work really hard for earlier.

2 other reasons your RV refrigerator freezes up

#1 Lack of ventilation

There could be vent blockages that are causing air circulation issues and thereby causing RV refrigerator freezing. Possibly, the fridge is placed too close to the back wall.

Lack of air circulation could also be caused because the vents need cleaning. They tend to get clogged with dirt and debris over time.

#2 The thermostat itself is covered in ice

If the thermostat is covered in ice, it may not be functioning properly. You should unplug the fridge, let the ice thaw around it and then plug it back in to test if it’s working fine.

How to defrost your RV refrigerator?

A lot of RV’ers online seem to promote the use of a hairdryer to provide heat to the ice and speed up the thawing process.

My only concern with this is that it may damage the fridge, since you’re blowing hot air at everything, and not just the ice.

The other thing that I personally wouldn’t recommend is to use a wooden spatula or some other sharp object to break apart the ice as it thaws. Unless you’re really careful, you may just end up damaging something inside the fridge.

My suggestion?

Keep it simple. Just unplug the fridge, put a small bowl in the bottom shelf to collect the melted ice water and… wait.

Your food isn’t going to spoil- as long as you keep the door closed, the fridge won’t lose more than 3-4 degree F over the next 6-8 hours.

Alternatively, you could also empty the fridge completely after unplugging it and leave the door open- this will speed up the entire process.

Is there a correct temperature for an RV refrigerator?

Generally speaking, you’re good if the temperature is in the range of 38-43 degree F.

One small caveat here is that if you have some processed meat, cuts, etc inside your fridge(not the freezer), then you should keep the temperature at 40 degree F or below, to ensure no spoilage.

Honestly though, as long as you’re roughly keeping within this range, it doesn’t really matter much what the exact temperature is.

For the sake of being specific, however- my research tells me that the most optimal temperature for your refrigerator is 38 degree F or 3 degree C.

In fact, if you start going below 38 degree F, there is a good chance your fruits and veggies are going to freeze.

Conclusion

There aren’t a lot many reasons why the inside of an RV refrigerator freezes.

If you didn’t find the solution by going through this post, I’d say you probably need to call a professional to come look at your fridge.

Hope you found the article informative and if you’re looking for a more in-depth guide on how RV refrigerators work, check out the page!

The master RV52 refrigerator how-to page is a great starting point for RV refrigerator research.

Find thermisters in the RV52 refrigerator database.