Why is My RV AC fan not working? Troubleshooting Guide for RV Air Conditioners
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Your RV air conditioning was working just fine until… well, something went wrong. The fan is blowing warm air – or maybe the AC won’t turn on at all – and your RV is uncomfortably warm. In order to troubleshoot your faulty RV air conditioner, start by using this RV air conditioner troubleshooting guide.
Why is my RV AC fan not working?
Common causes of the RV AC fan not working are a lack of cleaning or maintenance, a broken thermostat, mechanical problems with the fan blades, faulty wiring, and electrical problems.
Troubleshooting Your RV AC Unit: Before You Begin
When you first realize that your AC fan is not working, get prepared to diagnose and fix the problem.
Anytime you decide to do a DIY project on your RV, please ensure your own safety. Follow basic safety guidelines such as using the proper tools and wearing gloves and safety glasses.
Please note: You may need to get on the roof of the RV to work on live circuits or moving parts. Use caution, especially when coming into contact with exposed wires. Be very careful that you don’t cause more damage to your AC unit (or yourself!).
Ask for help when working on this for the first time or if you just don’t feel comfortable working on it by yourself.
Here are some related articles that may also help you along the way:
- Running an RV Furnace (Battery, Generator, 110)
- RV Keeps Tripping The Breaker? Here’s What to Do!
- Can RV Surge Protectors Get Wet? (And Other Important Questions)
What Tools are Needed to Fix RV AC Unit?
If you are nervous or have made mistakes handling electrical components in the past, consider driving the RV to a repair shop. There you can have a professional diagnose and fix the unit.
However, with the right tools and confidence, you should be well-equipped to assess and fix your unit on your own. Your best option is a small toolbox for your RV (Amazon).
To properly troubleshoot and fix your RV’s air conditioner, you must at least have a working knowledge of electrical and mechanical equipment and tools.
In fact, these tools are handy for many jobs. This multimeter is worth its weight in gold when checking electrical connections in an RV (or home). I recommend getting this multimeter on Amazon.
In addition, here’s a short list of tools you may need that we recommend keeping in your RV at all times:
*all our suggestions are available on Amazon
- Flashlight
- Electrical tape
- Voltmeter with amperage and ohm/resistance reading capabilities
- Multimeter
- Pliers
- Screwdrivers
- Safety glasses and gloves
- RV AC unit user manual
Types of RV AC Systems
Before you start cutting wires and exposing panels, make sure you have the user manual for your specific AC unit handy. Many different brands of RV air conditioners will have their own unique attributes.
This article will help you diagnose and fix common electric AC failures no matter the model or brand. However, most AC units fall into one of two categories. Knowing what type of AC unit your RV has can help you in diagnosing and fixing it.
The two main types of RV air conditioning units are:
- The Air-Moving System: This is made up of two fans and a motor. One of these fans pushes air through a condenser and the other through an evaporator.
- The Sealed Air Conditioning System: This consists of an AC unit’s technical inner workings, including a condenser, compressor, and evaporator.
Once you’re familiar with your RV’s AC system, you will have a better idea as to what components to check on and keep maintained.
10 Reasons an AC Unit is Not Working
You may be worried that your technical skills aren’t keen enough to troubleshoot and fix your broken AC. First, however, you should rule out these common reasons for an RV air conditioner fan not working:
1. The AC unit is old.
After years of use, even the best AC units won’t cool as well. It’s possible the AC unit is just worn out. If the motor is worn out it won’t move the fan blades. However, some worn-out parts of the unit are replaceable… so don’t give up hope yet.
2. The outside temperature is too high.
If it gets too hot out, the AC may struggle to keep up – which might feel like it’s not working. An RV AC unit can cool to approximately 20 degrees F lower than that outside air. So at 100 degrees Fahrenheit outside you will get the RV no lower than 80 degrees, which will still feel hot.
3. The weather is hot and humid.
The unit could freeze up when it is running. The humidity on the cooling coils can condense and freeze, especially if it’s running on high for an extended time.
4. Lack of maintenance on the AC unit.
The fins, coils, and air filters have not been cleaned for a long time, and they’ve collected a lot of dust or dirt. This is a common cause of AC failure, so check that your unit hasn’t collected a ton of grime affecting airflow.
5. The unit isn’t getting power or the breaker tripped.
Check that the circuit breakers on your RV are not tripped (if it is tripped, it will have flipped to the “Off” position). If they are, start by cutting off electricity at the main breaker panel. Then flip the breaker back on. You can then try resetting the breakers to see if power returns. (Learn more about tripping RV breakers here)
6. The thermostat isn’t set correctly.
The thermostat determines when the AC unit will kick on. It will be located on an interior wall of the RV. It needs power and to be set correctly. Make sure your thermostat is set to the “on” or “auto” position. In order to kick on, the thermostat temperature must be set to a lower temperature than the inside of the RV. Try various switch positions or vent settings. Try turning on the fan only. There may be a problem in the wiring for just one of the settings.
7. Inspect the inside of the AC unit for broken parts.
Turn off the electricity first, and be careful not to touch the capacitor or any wiring! Do you see any faulty wiring, or crossed wires, or notice a burnt smell? Also check to see if the fan is moving freely, as the blades or bearings may be stuck.
8. Check the wiring for the unit.
Follow the wiring on your AC unit to see if any wires are broken or damaged. It might mean unhooking RJ11 connectors to check the wires’ condition. If they appear normal, put them back in place. To avoid mistakes when reconnecting the cables, only track down a single wire at a time. Make sure to put it back in the right place before moving on to the next one.
9. Your start and run capacitors could be bad and need replacing.
Capacitors store energy to give a motor or electrical equipment an initial boost of energy to start. RV air conditioners have two capacitors: a motor start capacitor and a run capacitor.
Starting an AC unit requires more power than running the unit, so a start capacitor is needed. The motor must initiate the movement of the fan blades. Then a run capacitor ensures the cool air continues to flow.
The wiring diagram in your AC user manual will show you if there are the start and run capacitors on your AC. New ones can be easily purchased like this start/run capacitors on Amazon.
10. The thermometer needs to be reset
Disconnect the thermostat at the wall. If possible, disconnect the wire and reattach it again. Also, reset the thermostat by following the steps outlined in the user manual.
A thermostat can easily be replaced and is available on Amazon like this Dometic thermostat.
If the tests above failed to diagnose the problem, keep reading for some more technical advice and testing procedures.
RV AC Fan Troubleshooting Quick Reference
If you’re able to pinpoint the source of your AC problems to the fan, consult our Quick Reference Guide below.
Quick Reference RV AC Fan Troubleshooting Table
| A/C Fan Symptoms | Potential Problem Areas for Diagnosis | How To Fix |
| A/C fan won’t stop running | – Check compressor and capacitors – Check settings on thermostat | – Replace or repair the compressor – replace thermostat and set to “Auto” |
| A/C fan repeatedly turns on and off | – Check that capacitors are working – Check coils and air filter for dirt or grime | – Replace capacitor (amazon) – Check power flow to the unit – Clean coils and air filter |
| A/C fan won’t turn on at all | – Check if breakers are tripped – See if fan motor may be broken | – Ensure power flow to the unit – Flip tripped breakers – Clean out blockage between fan blades |
| The compressor won’t turn on, but the fan does | – Check for a bad thermostat or capacitor – Double-check the temperature setting | – Replace thermostat or capacitor (amazon) |
| A/C fan speed is inconsistent | – Test motor voltage – Check for buildup at the blade base | – Replace motor for proper/functioning voltage – Clean unit |
| A/C fan makes an unusual noise, like whistling or scraping | – Remove the shroud (unit cover), check for interference with the motors – Check for clogged filters or vents | – Remove debris, test capacitors and compressors |
| A/C fan makes a humming noise but won’t turn on | – Check for damaged compressor, coils, capacitors – Check voltage | – Replace capacitors and/or compressor – Clean coils |
| Airflow at the vent is very weak | – Check the unit for dirt or leaves – Minimize other power uses | – Clean the condenser coil, components coils, evaporators, etc. – Make sure you’re operating within your RV’s power capabilities |
| Airflow from the A/C is not cold | – Check the fan motor, coils, and fins – Check for loose wires or low battery – Double-check temperature setting on the thermostat – Check RV AC unit Freon or refrigerant levels | – Clean or replace the fan motor, coils, or fins as needed – Refill refrigerant if necessary |
Specific RV AC Problems
Still stuck?
The following are some more specific issues you may be having with your RV AC:
- A strange noise comes out of the AC unit when it turns on. This might indicate that some of the controls and units are not receiving enough power.
- The AC fan fails to start, is slow to start, blows warm air, or keeps tripping your circuit breaker. This may mean there’s something wrong with the capacitors.
- The AC only works when the thermostat wires are connected. The thermostat is likely broken, so have it replaced.
- The AC is not working, but the control board looks okay. Try replacing the fan motor, compressor, or both.
- If the AC unit overheats, replace or clean the coils.
- Water is leaking out of the AC unit. Water could be condensing in a place where the fan can’t reach it to turn it into moisture. Cleaning the coils will fix this.
Hopefully, by now you have narrowed down the root cause of why your RV AC isn’t working correctly. If not, it may be time to get up onto the roof of the RV.
Checking the AC unit on the Roof Of Your RV
If, at this point, you’re still at a loss and your RV is getting warmer by the second, you’ll need to get up on your RV’s roof for additional inspection and tests. These may be a bit more technical than our earlier tests.
*Please seek professional help if you are not comfortable working on your RV at this point or if you’re not in a position to get up on the roof safely.
Electrical Inspection of RV Roof AC and Control Board
- When you get to the roof, unhook the AC cover (aka shroud). Inside, you will see the control board, electrical elements, motor.
- Check the wires. Determine if any of the wires on the control board are burned, disconnected, or loose.
- Check for discoloration or smells. The control board components should not be burned or discolored in any way. Also, there should not be a strong smell of burned plastic.
- Check the insulation. Ensure it is in good condition and if any of the wires are broken or out of place. If either is true, replace or fix it and move on to the next thing.
- Is the motor getting power? If it is, you should be able to read it from your voltmeter. The meter will also tell you whether the power registers within the proper amperage.
- Check wires for continuity. Use a voltmeter to check for continuity in case of higher-than-normal amperage. This could occur if the wires are corroded at any point in the connections. It may be necessary to open them up and redo every connection, going back to the circuit breakers.
- Is the thermistor working properly? A thermistor is a common type of AC temperature sensor used to send signals to a control board. Since these are sensitive to temperature, they should be tested with heat. This can be done using a multimeter if you have one.
- Is the control board damaged? If you notice there’s been severe damage to your control board, an expert at a repair shop should be able to repair this.
At this point, if the AC still won’t work, you can move on to check the condition of the relays and capacitors. This requires getting into more technical aspects of the job. Again, seek professional help if this is beyond your level of skill or comfort.
RV AC Humming but Fan not Running
You may turn on the AC unit and hear it humming, yet the fan is not running.
This could mean there are not enough amps for the unit to start up or you may have a faulty fan run capacitor or start capacitor. These are easy to buy on Amazon like this start/run capacitor
Make sure you have enough amps from your power source. Ensure you’re plugged into the correct 30 or 50 amp outlet that your RV requires. Also, check that your extension cord is not too long and is the correct gauge wire.
If the fan is stuck it will be difficult to rotate by hand. You can easily tell if a blade is bent or stuck by looking at and feeling it. It may also just be gunked up from sitting over the off-season. A gentle nudge should get it going again.
A faulty fan start-up capacitor is cheap and easy to install. Cut the power, open the AC unit, and take the old capacitor out. Make a note or a photo of where the wires go before unhooking any wires. Install the new capacitor, making sure to plug the wires in the correct order.
This is the most popular (and reasonably priced) RV AC capacitor on Amazon
Pro tip: If you are unsure of which capacitor to buy, you can take the old one with you to the electronics store.
Tips For Maintaining and Cleaning Your RV AC
We hope that by now you’ve been able to fix the issue and are cooling off. Now that your RV AC is back in working order, make sure to prevent future problems by regularly cleaning and maintaining the unit.
Maintaining Your RV AC
- Keep an eye on the thermostat settings. You may be inclined to keep the settings at “low” at all times during the hot season, but this can also drain your RV. Whenever possible, leave the thermostat set at “auto” so the temperature will adjust itself automatically.
- Whenever possible, open the roof vent or windows instead of running the AC.
- Oil the AC fan regularly. (Pro tip: use mechanical oil, not WD40)
- When the RV is not in use, keep the AC unit covered up to prevent damage and the usual wear and tear.
- The condenser coil will accumulate dirt. You must remove and clean this occasionally to keep airflow uninterrupted.
How to Clean Your RV AC
Here are tips on how to clean your RV air conditioning unit to keep it running smoothly:
- To prevent injury, unplug the unit before starting your cleaning process.
- Start with the filter. If your unit gets regular use, clean the filters every few weeks with warm water.
- Let the filters dry out and, if torn or damaged, replace them.
- Clean the evaporator coils. Once you get the unit’s filters off, the coils will be accessible and can be cleaned using a small brush.
- Clean condenser coils. Get to the top of the RV and unhook the AC’s shroud to clean the dust.
- Purchase an AC coil cleaner spray to use here, but avoid damaging the cells.
More Tips for Stress-Free Travel
Aside from RV AC troubleshooting, there’s still a few more things to keep in mind for a fun, safe and easygoing camping experience.
Visit my Etsy store to download the best printable journal and checklists to help keep you on track when prepping your RV for travel.
The RV Camper Trailer Preparation Journal will help keep track of the daily ins and outs for all your RV needs. This simple tool has helped ease my mind countless times and I’d be delighted to know that it did the same for you.
In addition, my RV Campground Arrival Setup checklist will make sure you don’t skip a beat getting your site set up quickly and correctly to ensure a stress-free getaway.
Have more questions on RV maintenance or maximizing longevity? Here are more articles that you might find helpful:
- How Long Do RV Rubber Roofs Last? (Plus 7 Maintenance Tips!)
- A Guide To Winterizing Your RV (Temperatures And More)
- Towing Capacity Guide (Without Trailer Breaks)
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