Dometic RV Air Conditioner Troubleshooting – 3 Common Issues, 6 Less Common Issues, How to Fix It, and Maintenance Tips

Boy is it hot, right?!

If you’ve already tried troubleshooting your RV’s AC but nothing worked, this guide is for you.

We’ve experienced faulty issues in our AC too often we’ve decided to share a guide on the most common culprits and how to solve them.

Below is the best troubleshooting guide for your RV air conditioner.

Top Three Issues of RV Air Conditioners – How to Solve Them

Even with the best maintenance and proper care, air conditioners will have issues from time to time.

If it’s your first time experiencing any of these issues, know you are not alone.

Important Reminder! Before performing any repairs on your RV AC unit, make sure the unit is turned off. Disconnect it from the power source to avoid any electrical shock and further injuries.

Issue #1: The RV Air Conditioner Has No Power and Won’t Turn on

Due to long years of experience, we can assure you that if this is your problem, most probably, the issue lies with the power supply or the breakers.

Troubleshooting Guide:

Possible Cause #1:

The first place to check would be the circuit breaker. Make sure no breakers were tripped and that you don’t have blown fuses.

Another thing to take note of is the power consumption of your RV.

Possible Cause #2:

Do you have enough power in your vehicle to run an AC unit? This is often overlooked by a lot of people, especially when the RV Air Conditioner unit is power-sharing with other appliances.

When this happens, you can minimize the consumption of other appliances so that your RV air conditioner receives the power it needs.

Possible Cause #3:

Using a generator and the air conditioner does not turn on? This is usually a transfer switch issue. The wires of transfer switches can get pitted, corroded, and in some situations, even come loose.

The best way to address this situation is to replace the faulty RV transfer switch with a new one. You can watch how to replace a faulty switch here.

Issue #2: My Air Conditioning Unit Won’t Run

At some point, RV owners get alarmed because their Dometic air conditioner is on but won’t start.

When this happens, the problem may lie in any of the following:

  • Fault codes
  • High-pressure switch circuit
  • Capacitors
  • Thermostat

Troubleshooting Guide:

Possible Cause #1:

RV air conditioners will display fault codes when they are encountering problems. Once you see the fault code, check your owner’s manual for its meaning.

From there, the manual will tell you what you should do.

Possible Cause #2:

Some Dometic air conditioner units have a high-pressure switch circuit. This could be caused by unfavorable conditions such as dirty air filters.

When this happens, we advise you to reset the circuit. Some models can be easily turned on and off, while some may require you to check the owner’s manual for steps to reset.

Possible Cause #3:

Hearing a humming sound? That’s oftentimes your capacitors needing your attention. Your RV air conditioner has two capacitors, namely the run capacitor and the start capacitor.

Not sure which one is not working well? You can test both your capacitors with a standard multimeter. The bad capacitor will need to be replaced by your manufacturer.

Possible Cause #4:

Lastly, check the thermostat.

Most people rule this out when troubleshooting their air conditioners. Remember, the temperature must be low enough for the unit to power through.

Issue #3: My Air Conditioner Is Not Blowing Cold Air

Isn’t it annoying when your air conditioner is not blowing cold air? It had one job, right?

Don’t worry, we’ll tell you all the tips you need to get your air conditioning to keep your RV cool in no time.

Troubleshooting Guide:

Possible Cause #1:

First things first, check the temperature outside of your RV. Most of the time, the temperature outside recreational vehicles makes it difficult for your AC unit to function.

This usually happens when your RV air conditioner has a high heat gain.

Possible Cause #2:

Aside from having a hot temperature, other reasons that make it harder for the RV to blow cool air are when the vehicle is poorly insulated, is parked directly in the sun, or when there is little to no wind present.

Also, you can check if the thermostat is set incorrectly. Ensure that it’s set to cool and not to blow hot air.

If it’s not set to cool, switch it back to the cooling operation and wait for a few minutes. It should already be blowing cool air by then. If it is, then you have resolved the problem.

Possible Cause #3:

However, if it’s set to cool and still blowing warm air, the problem may lie with your air filters and condenser unit.

Other Issues Worth Mentioning

Dirty Air Filters

An air filter cleans the air that circulates in the heating and cooling system of AC units. Their job is to trap dust, allergens, and other rubbish from entering your RV. [R]

It’s totally normal for your air filter to get dirty, as its role is to trap dirt. However, this may lead to reduced cooling as the accumulated dirt blocks the airflow of cool air.

To fix this issue, simply clean your air filter weekly with soap and water. This way, you can rest assured that your AC’s filters will function in tip-top shape.

Blocked Condenser Coils/Evaporator Coils

Just like the air filter, the coil is another part you’ll have to check when your AC system is not producing cool air anymore.

Sometimes, your RV air conditioner coils are clogged or blocked. When that happens, heat is not released into the outdoor air, which makes the air inside warmer.

To clean dirty coils, use a simple solution of water and dish soap. A sponge or a soft brush will do the trick to wipe the blockage away.

Tip: There are also solutions specialized for condenser coils and evaporator coils. If you can’t find some, water and soap will work just fine.

It’s important that you regularly clean your condenser and evaporator coils. This will prevent high-pressure switch circuit tripping.

Low Refrigerant Levels

Your refrigerant, or the coolant, is what makes air conditioning possible.

With low levels, you will notice that your power consumption goes up, as the RV AC needs to work harder to convert warm air to cold air. [R]

We recommend you leave this one to a qualified technician. Checking the air conditioner’s refrigerant levels requires expertise.

PLUS, a technician will be able to determine if the refrigerant already needs to be replaced.

Old Air Conditioning Units

I’m sure you took proper care of your RV AC.

But, as they say, there will come a time where you need to replace it. Not because they don’t work anymore, but because they don’t function like they used to.

The older your RV AC gets, the harder it has to keep up with the demands of blowing cold air.

If your AC unit has been at your service for years, then it’s time for a new RV air conditioner.

Less Common Issues of Your AC Unit and How to Fix Them

#1 Ice on Your RV Air Conditioner

Although they don’t usually happen, freeze-ups do occur every once in a while.

They can happen due to a variety of reasons such as dirty evaporator coils, excess humidity, a faulty thermostat, or Freon leaks.

Solution:

The first thing to do is to check if there are any leaks.

If there are none, simply go to your thermostat and switch the mode of your RV AC to “fan high” instead of “cool”. Give it a few minutes and voila! No more ice!

#2 My AC Unit Gives off a Foul Smell

It’s not usually a good sign when there’s a foul smell, right?

The usual cause of a bad odor is dirty or torn filters. An AC unit with a torn filter will easily accumulate dirt, leading to a foul smell.

Solution:

The best way to go about this is to clean your filters.

However, if you’ve already tried that and it still doesn’t work, your filters may need to be replaced.

#3 Air Conditioner Doesn’t Stop Running

Cold air makes your RV comfortable, but too much cold isn’t good too.

An AC unit that does not stop running could have a busted thermostat or a faulty circuit board.

Solution:

We advise you to replace a bad thermostat with a new one.

Similarly, when you encounter a faulty circuit board, we recommend you seek the help of a professional to avoid any incidents.

The technician will know if a blown fuse is present and can still be fixed, or a new one for your air conditioner is recommended.

#4 Leaky RV Air Conditioner

Believe it or not, the leaking of an AC unit is a common problem RV campers face. This may be due to a clogged drain pan.

Solution:

To clean an RV air conditioner, simply follow these steps:

  • Once you have the air conditioner, remove the outer cover of the unit, or what is usually called the shroud.
  • Remove the inside cover if the shroud is not visible after removing the outer cover.
  • Drain the water from the shroud. This also removes debris stuck in the pan.
  • Dry the condenser coil/evaporator coil and the shroud with a damp rag.

An RV AC unit is usually sealed to the rooftop with a rubber gasket.

A leaky unit might mean the gasket is no longer intact, which you can easily remedy by replacing it with a new one.

You can either ask a professional to do this for you, or you can also do it yourself. We will talk more about this below.

#5 Air Conditioner’s Motor Is Really Loud

What’s more annoying than a really noisy AC unit, right?

A new air conditioner runs smoothly and quietly in the background, so how can it go back to the way it was before?

Solution:

There are multiple ways to make your air conditioner quieter.

The first thing to do is to inspect all the bolts of your AC.

Make sure the screws are not too tight. Try loosening them up a bit if you think they are too tightly screwed.

Another part to check is the rubber shock absorbers of your RV air conditioner.

Most likely, they are out of place and are in contact with other parts of the RV AC, such as the AC compressor coils and fan motors.

It is also possible that they are worn out. We advise you to replace it with a new rubber shock absorber so you can minimize the noise your RV air conditioner makes.

#6 My RV AC Only Produces Hot/Warm Air

The purpose of air conditioners is to be able to sustain blowing cold air inside your RV, right?

To avoid being frustrated over how warm it is in the summer, check your motor voltage first.

Is the AC not getting adequate voltage? We advise you to seek the help of a qualified technician.

Solution:

If you find that it is still not working despite receiving ample voltage, we recommend you purchase a brand new AC unit.

Proper Maintenance of Your Air Conditioner

The old adage “prevention is better than cure” still rings true.

Taking care of your AC unit is easier than you think, not to mention that it’s going to save you a lot of time AND money in repair costs.

Regular maintenance will also benefit you in the long term, as it lowers down the chances of your RV air conditioner breaking down in the middle of nowhere.

We don’t want you to go through that inconvenience.

Here are tips on how to perform regular maintenance on your AC:

  • Lubricate the fan motor. When your RV air conditioner turns clunky, it’s time to check up on your AC unit motor. Just to be sure, check your owner’s manual to see what kind of oil your unit needs. You may also want to contact your RV manufacturer to make sure you have the right oil. Otherwise, you may lubricate your blower motor with a non-detergent-type oil.
  • Regularly clean the coils. You don’t have to do this on a weekly basis, but AT LEAST ONCE every year, check if there is already blockage in your coils. Don’t wait for the hot air to indicate your AC needs cleaning. You may use either a handheld vacuum or a soft bristle brush to remove the dirt.
  • Clean the A/C Box Housing. Both the distribution box and the control board are important. To do this, you may use an air conditioner coil cleaner or mix warm water with a few drops of dish detergent.
  • Cover your RV’s air conditioning unit when not in use. When you come to think of it, your air conditioner is a magnet for all kinds of dirt and dust. Part of the basic maintenance is putting a cover on your rooftop AC unit when it’s not running.
  • Clean your filters every two weeks. Do you want your AC units to keep blowing cold air? The secret is in checking your air filters every two weeks. Have we mentioned that this increases the lifespan of your air conditioner?

FAQs

How Do I Replace an Old Rubber Gasket?

The first step is to verify if the rubber gasket is intact. Is there at least half an inch of height between the gasket and the air conditioner itself?

If there is, then good. However, if there is not, then you would have to replace the gasket already.

To do this, follow the steps enumerated below:

  • Remove the outer part of the AC.
  • Locate the bolts inside and remove them.
  • Detach the AC unit from the roof vent.
  • Make sure the power is disconnected before cutting the three wires with cutters.
  • Now, you can get the old rubber gasket and replace it with a new one.*
  • Reconnect the wiring and then reattach the outer part of the AC.
  • Verify if the new gasket is working properly by lightly spraying the unit and checking if there are any leaks present.

*Note: Sometimes, the gasket is especially hard to remove or it’s stuck. When this happens, use a knife.

How Can I Make Sure That My Unit Is Receiving Enough Power Supply?

Everyone knows all kinds of air conditioning require VERY high voltage power, even a new unit. This is equivalent to 15 amperes.

Fortunately, owners of RVs can rest assured that RV parks are capable of providing more than enough power. Most campgrounds and parks nowadays are ready with 50 amperes.

You don’t have to worry now, your A/C will be able to handle blowing cold air and keeping the temperature of your RV cool.

Is It Normal for My RV Air Conditioner to Be Surrounded by Ice?

As much as its job is to continue blowing cold air, your unit SHOULD NOT be surrounded by ice.

This is usually an issue with your AC’s freon. There is a high chance that a leak happened.

However, there is also a possibility that you need to increase your refrigerant levels so that the AC’s coils can function properly.

Remember, it is possible to produce cold air WITHOUT the AC producing ice.

How Can I Replace and Remove a Fan Motor on My Own?

Here are DIY steps for you to clean your AC’s fan motor:

  • Remove the power source of the unit before removing the dirt and dust.
  • Detach the grill of the AC so you can vacuum the fins.
  • Remove the wiring and the fan motor.
  • Replace with the new motor.

How Do I Reset My Unit?

Honestly, a lot of people reset their air conditioners when they have noticed that it’s not functioning properly anymore.

When this happens, we advise you to change the settings such as the temperature set-point. This will be displayed on the LCD screen.

Can I Recharge My Air Conditioner?

Absolutely! BUT, it depends on the type of your AC. Some models are easier to recharge than others.

No worries, though. You can count on us to teach you the basics.

  • Find your AC’s power panel and shut off the power. Remember to turn off any breaker that may be a power source to your AC.
  • Identify the coolant your AC uses through the owner’s manual. DO NOT mix brands. Doing so can heavily damage your unit. In this one, it is better to be safe than sorry.
  • Remove the plastic lid or the cover of your unit. Make sure to lift straight up to avoid damaging any coils. It is also possible to find a nest of insects inside. Remove it immediately.

Related

Some Final Words…

Learning how to troubleshoot your RV air conditioner will save you lots of time and money.

Not to mention that it might as well be a necessary skill to learn if you are someone who travels in your RV for long periods of time.

Just remember that if it is your first time encountering a problem, especially one that involves compressor coils, faulty circuit panels, and tricky wiring, make sure to seek a technician’s help.

While it’s great that you are trying to learn how to troubleshoot on your own, we’re still dealing with electrical appliances here, and your safety is the most important.

We hope you learned something from this article about RV troubleshooting. Stay safe and wishing you safe travels!

12 thoughts on “Dometic RV Air Conditioner Troubleshooting – 3 Common Issues, 6 Less Common Issues, How to Fix It, and Maintenance Tips”

  1. The rooftop air conditioners used on motor homes are made in such a way to provide many years of dependable use. Especially if you maintain them. These repair and maintenance tips are very simple to follow, even for those without much hands-on experience. Thanks for sharing these great tips.

    Reply
  2. I live on a boat, I went on vacation, turned it off I come back and now it’s not working, maybe the compressor? It’s only two years old, what should I do?

    Reply
  3. I found it interesting that you state that it’s important to have AC when you’re driving in the heat. My brother and his wife want to buy an RV and cruise the country. I will send them this information so they can make sure to get a good AC unit for their trips.

    Reply
  4. My a/c worked but after a move .It now dont work . I blows cool air and has a smell. Crazy a 90 mile trip caused not AC . Any tips would be grateful.

    Reply
  5. AC runs and blows cool air. After running for several minutes the blower will shut down and compressor will continue to run, then a few seconds later the blower comes back on. This continues until cooling tempature is reached. Is this common?

    Reply
  6. I bought a new trailer with a 135000 btu ac. It would come on for two mins and go off for two min. Looking at the papers that came with trailer I saw there was a duct divider that needed slots made in it.i removed divider and put the amount of slots needed for the height of unit. Problems solved! I’ve searched for this problem on internet with no one offering this as a solution. Please post this for me as I dont know how to.

    Reply
  7. txbjmster@gmail.com
    I picked up my Dads motorhome after he had a new Dometic roof
    top unit installed. I can hear the compressor
    come on but it blows hot air. Could the crooked
    man that installed it have hooked the compressor
    backwards. It gets hotter when the compressor
    comes on.

    Reply

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