Nothing is worse than being out on a road trip and discovering your RV air conditioner has frozen up, it’s certainly a frustrating experience that usually happens at the absolute worst time.
Having recently been through this very same issue, I decided to put together a helpful guide on the 10 common causes, fixes, and prevention based on my research and experience.
So why do RV air conditioners freeze up? The common reasons for RV AC Freezes are;
- A bad or broken thermostat.
- Very high humidity levels.
- Low coolant levels.
- A bad capacitor.
- Defective freeze sensor.
- Very low outside temperatures.
- An obstructed air conditioner unit.
- A bad flow divider or baffle.
- Dirty evaporator coils or dirty condensers.
How To Defrost Your RV Air Conditioner
If the air conditioner in your RV has frozen up, you will first need to defrost it. Obviously, you cannot use a frozen air conditioner, so this is absolutely necessary.
Follow the steps listed below to defrost your RV air conditioner in as little time as possible;
- You will likely need a screwdriver and a pry bar to remove the cover from the air conditioner unit. You will most likely need to access the air conditioner from the interior of your RV.
- You are now going to turn the air conditioner on to its highest setting. Be sure that you only turn on the fan. Here you are not actually turning on the cooling function.
- This will cause the air conditioner to defrost. To catch the water that runs out while it is defrosting, put a bucket or some towels below the air conditioner.
- Once there is no more water coming out and everything looks totally dry, allow the air conditioner to sit for a while so it can totally dry out. To allow for it to dry faster, you can continue running the fan.
What Causes RV AC To Freeze Up?
Here are the most common causes for a camper AC freezing up and most importantly how to fix the issue yourself.
These fixes are universal, so regardless if you have a Dometic, Coleman, or even a brand new AC the same process applies as they can all be subject to the same issues.
1. Your AC Unit is Being Obstructed
One of the common reasons is due to some kind of obstruction. This could be an animal, debris, birds’ nests, or anything else of the sort.
If this is the case, you will see obstructions around the coils on the inside or the outside of the air conditioner’s housing.
The obvious solution here is to inspect the exterior to ensure that there are absolutely no obstructions. If you think that there may be some kind of birds nest on the interior, you will have to take the air conditioner apart. Simply click, remove any and all obstructions that may be present.
2. Dirty Evaporator or Condenser Coils
Perhaps the most common reason is due to limited airflow. Limited airflow is often caused by blockages in the evaporator coils or the condenser coils.
Keep in mind that condenser coils are designed to move heat outside, whereas evaporator coils remove heat from the air. If these items aren’t cleaned regularly, they have to work much harder than they usually would.
The debris that forms on these coils well then block the air conditioner from functioning properly, which will then cause ice to form on the coils.
To clean the evaporator or condenser coils, you’re going to need a shop-vac, a cloth, a screwdriver, a spray bottle, and some soap. You’re probably going to have to get up on the roof of your RV for this. Make sure that everything has been unplugged so there’s absolutely no power running through the air conditioner unit.
You then need to screw away the cover from the air conditioner unit. Keep in mind that most air conditioners on recreational vehicles have the evaporator coils in front of the condenser coils, which are at in the back.
You are now going to use your cloth, shop-vac, and vacuum to remove any and all debris that is present. Just make sure that you don’t knock any of the debris into any of the openings that go into your RV.
You’re now going to mix some water and soap to spray down both the condenser coils and the evaporator coils. Let this soak in for a few minutes, wipe it down, and then vacuum again.
If the coils are still dirty, repeat the process. Once everything is clean and ready to go, you can put everything back together, turn the power back on, and see if the air conditioner is now working.
3. The AC Filter Is Dirty
Another common cause of air conditioner freezing up in RVs is due to reduced airflow caused by a dirty filter. First and foremost, the filter in your AC unit in your RV should be replaced annually.
You should then also be cleaning it about once per month, especially if you are using it heavily. If you don’t want to bother with cleaning, replacement filters aren’t all that expensive. So, if you think this may be the cause, open up your air conditioner and inspect the filter.
If the filter is dirty, simply use a cloth to wipe away any debris and dirt. You may then also want use some water and soap to wash the filter. Seeing if the filter is dirty is very easy. If that mesh is covered in debris, then it’s time for a cleaning.
4. The Exterior Temperature Is Too Low
Yes, a lot of us like to have it really cold. With that being said, there is only so cold that you can go without causing problems with your air conditioner. For instance, most air conditioners installed in recreational vehicles cannot deal with outdoor temperatures that are 65 degrees Fahrenheit or lower.
If your air conditioner is sucking in that already cold air and then attempting to cool it down even further, it may cause it to freeze up. Simply put, it’s too cold for your air conditioner. If the exterior temperature is below 65 degrees, do not turn on your air conditioner unit.
If you do need to cool down, and it is that cold outside, just open up the windows. This is no different than using a space heater when there is already a heat wave going on. It’s just absolutely senseless.
5. A Broken Thermostat
The thermostat contains a thermometer that senses the ambient temperature. Now, this does of course only apply to air conditioners that have a thermostat control. Some of these just have on and off settings, in which case you don’t need to worry about this issue.
Moreover, if you do have a much older thermostat, it may just be broken and no longer functioning, in which case you want to change it. Generally speaking, broken thermostats need to be replaced, and usually can’t be repaired. They may be repairable in some cases, although how cost effective this will be is questionable.
To test your air conditioner thermostat, use a different thermometer to test the interior temperature inside of your RV. You then want to compare that temperature to the temperature that you have the air conditioner set to. If the numbers don’t match up, then the thermostat is having problems.
Most people should be able to do general thermostat replacements and air conditioner units with minimal electrical experience. However, if you don’t feel comfortable working with electronics, you will need a professional.
6. A Bad Baffle or Flow Divider
The baffle in your air conditioner may also be known as a flow divider. This is a very important mechanism as it keeps the cold air that blows out of the unit separate from the hot air that comes in.
If there is an issue with that flow divider or baffle then these air flow supplies can leak into each other. If the two leak into each other, it may cause your air conditioner unit to freeze up.
To deal with this issue, you’re going to need to open up your air conditioner to see if the baffle or flow divider is in the proper position. If it is not in the proper position, you need to put it back in place.
Moreover, if there are any leaks, using some HVAC foil tape to seal those leaks is recommended. However, if the baffle or flow divider is extremely damaged or broken, you will need to replace it. In some cases, these may not be replaceable and may actually require you to replace the air conditioner unit as a whole.
7. Issues With The Freeze Sensor
Although this is not always the case, some recreational vehicle air conditioners do come with a so-called freeze sensor that is mounted on the evaporator coil fins.
These are special sensors that have the ability to detect ice, and will then shut off the compressor so that warm air can defrost the coils.
If this sensor is defective, has fallen off, or is not properly placed, it won’t be able to stop your air conditioner from freezing.
Here, you are looking to ensure that this freeze sensor is located about halfway up the coils. You don’t want the sensor to be dangling freely, and you don’t want it to be too far up or down along those evaporator coils.
If the freeze sensor is in the proper position, it might just be broken, in which case you will want to replace it.
These generally don’t cost more than $50, so replacing it shouldn’t be much of an issue. However, if you don’t feel comfortable replacing it on your own, you are going to have to call a professional for help.
8. High Humidity Levels
The fact of the matter is that an air conditioner does of course remove moisture from the air to cool the air down before it blows that air into your recreational vehicle.
Now, the more humidity there is in the air, the heart of your air conditioner has to work to remove that humidity from the air. The more moisture there is present in the air, the more moisture there is that can freeze on the coils.
This is often the case when there is a high level of humidity combined with you not having your air conditioning turned up to a very high degree. If you do want to prevent this from occurring, a good solution is to simply use a dehumidifier in your recreational vehicle.
However, if this is not an option, you can always turn the air conditioner up to its highest setting. Keeping the air flowing very high will prevent moisture from freezing on the coils. You can also just try opening up some ceiling vents in your recreational vehicle to rent moisture out as needed.
9. Low Coolant or Refrigerant Levels
Air conditioners use either coolant or refrigerant to cool down the air. Now, it is actually very uncommon for your coolant or refrigerant to leak. This is because air conditioners have so-called closed loop systems, which means that there should be nowhere for the refrigerant to go.
However, if there was some kind of damage, there may be a whole that is allowing the refrigerant to leak out. Corrosion, vibration, and heavy impacts can cause this to occur. However, the big issue here is that due to these refrigeration units featuring closed loop systems, you can’t actually add any refrigerant yourself.
Unfortunately, if this is the case, your air conditioner may be so damaged that you need to replace it. However, if you aren’t quite ready to give up, you can always go to RV service center to have them repair the coolant leak for you.
10. A Bad Capacitor
The 10th and final problem that your air conditioner may be experiencing that is causing it to freeze up is if the fan capacitor is bad or has malfunctioned. If the fan capacitor does not work, then the blower motor that blows cool air into the army will not be able to start.
This means that the compressor is going to run, but the cool air is not going to be pushed away from the air conditioner. This cool air will then cause the coils to freeze.
Moreover, if the capacitor fails or is just very weak, it may cause the compressor to not turn on at all, which will mean that the AC will not work at all.
What you need to do here is to use a multimeter to see if the capacitor is failing or bad. If it’s the capacitor is broken, you will need to replace it.
If you do not feel comfortable replacing the capacitor on your own, you will need to visit RV specialists to have professionals take a look at it for you.
Related: Do all pop-up campers have AC?
How To Keep RV AC From Freezing Up
There are in fact a number of things that you can do to stop your RV air conditioner from freezing up in the first place.
Of course, the number one thing that you need to do is maintenance. You need to maintain the filter and all other components. Regularly inspecting the air conditioner will also help to ensure that all of the components are in working order.
Remember, you want to inspect the baffles, the filter, the coils, and everything else that we have discussed above so far today.
However, there are then also other things that you can do to stop your air conditioner from freezing up.
Regular Cleaning of Filters
We did just mention this above, but we do want to stress the fact that regularly cleaning the air vents and filters in your air conditioner is going to help a lot. Dirt, dust, hair, and work in don’t get sucked in into these air vents and filters.
If you don’t clean them out, it will prevent air from flowing properly, and will then cause the air conditioner to freeze up.
Remember that you always want to check for obstacles and obstructions that may be preventing air from being properly sucked into the air conditioner in the first place.
Use LED Lights
Another good way to stop your air conditioner from freezing is to stop using it as much. There are other ways to keep your RV cooler.
For instance, if you switch to LED light bulbs as opposed to incandescent light bulbs, you’re automatically going to have a much cooler RV. Incandescent lights just put out way too much heat.
Cooking and Humidity
If you do have to cook in your RV, try to keep the windows open. Cooking is going to create a lot of moisture, especially if you are boiling liquids. Remember that high humidity levels inside of your recreational vehicle can cause the air conditioner to freeze up.
Therefore, keeping moisture to a minimum is ideal, and having a dehumidifier is definitely going to help as well. If humidity is an issue, running your air conditioner on the highest setting will help prevent it from freezing.
Park in the Shade
The less the air conditioner in your RV has to do, the less likely it tends to freeze up. Therefore, a good idea is to always park your RV in the shade.
Of course, the sun is going to heat up your RV to a great degree, so keeping out of the sun is going to help. Also, if it is night time, you may as well just open your windows up instead of using the air conditioner. This will also help you save energy, and therefore money too.
Related: If you have other AC-related issues we have covered a good troubleshooting guide here.
Will Frozen AC Fix Itself?
In most cases, a frozen air conditioner will not fix itself. If your air conditioner is freezing up and you don’t take the necessary steps to address the issue, it could cause further damage to the unit or even lead to a system breakdown.
If you notice that your AC has frozen up, it’s important to take immediate steps to thaw the unit and fix the problem.
If you don’t address the issue, it could lead to a more serious problem like a major compressor failure or even an electrical fire.
Is It Bad To Run Frozen AC?
Running a frozen air conditioner is not recommended. Not only will this cause more damage to the unit, but it can also potentially be hazardous to your safety.
When the AC unit is frozen, it restricts airflow and causes a buildup of pressure in the system which puts stress on the components. This can lead to poor performance or even an electrical fire.
There you have it folks, you should now know all of the possible causes of your air conditioner in your RV freezing up. Figuring out exactly what the problem is will take a bit of work.
However, once you do figure out what the problem is, it is generally something that you can solve on your own. However, if you do not feel comfortable working with your AC unit, then you will need to contact professionals for assistance.