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Your RV air conditioning was working just fine until well… something went wrong. It’s not working and your RV is uncomfortable warm. . Without any clear indication of what the problem might be, what can you do? Consulting the RV AC Fan Troubleshooting Guide is a wise choice.

Several common air conditioning problems are possible. Knowing how the AC units work could save you a lot of trouble if yours fails.

To fix your RV’s air conditioning, you must at least have a working knowledge of electrical and mechanical equipment and tools that make the job easy and safe. Here’s a shortlist of tools you need:

  • Flashlight
  • Electrical tape
  • Voltmeter with amperage and ohm/resistance reading capabilities
  • Pliers
  • Screwdrivers
  • Safety glasses and gloves

This article explains many of the problems you are likely to encounter with your RV’s AC unit. We offer solutions that everybody can apply to save time and money.

RV air conditioners are available in various brands. However, with this article, you will be able to diagnose and fix common electric failures involving your AC fan no matter the model or brand.

You’re going to get up on the roof of the RV to work on live circuits and other moving parts. This means you’re going to have to take precautions, especially when coming into contact with exposed wires. Be very careful that you don’t cause even more damage to your AC wiring (or yourself!).

You should 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 would also help you:

Safety First When Troubleshooting Electrical

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Whatever type of DIY project you do on your RV, ensure safety by following basic guidelines such as using the proper tools and wearing gloves and safety glasses.

If, you are nervous or you’ve made mistakes handling the electrical wiring in the past, consider driving the RV to an AC repair shop. There you can have an electrician diagnose and fix the unit.

In this guide, you will only learn the basics of diagnosing a broken RV air conditioning unit. Still, if there is a need to perform extensive electrical repairs on other parts of your RV AC, we recommend bringing in a professional.

How To Diagnose Why Your RV AC Is Not Working

This step will require checking things on the inside and outside the RV, so get ready to do all kinds of tests and inspections.

  1. Check that the circuit breakers on your RV are not tripped. If they are, start by cutting off electricity at the main, and then turn it on again. After this, you can try resetting the breakers again to see if it brings back to power. (learn more about tripping RV breakers here)
  2. Check that your thermostat is set to the on or auto position. To kick on, the temperature must be set to a lower temperature than the inside of the RV.
  3. Try various switch positions or vent settings. Try fan only. There may be a problem in the wiring for just one of the settings.
  4. Inspect the inside of the AC unit in your RV. (*Turn of electricity first!) Go to the unto and open the cover. (Be mindful of the capacitor) Does anything look out of the ordinary? Check for faulty wiring, a burnt smell or crossed wires.
  5. Inside the AC unit check the mechanical operation by manually moving the fan blade. You might find a problem with the fan blades or bearings.
  6. 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 and 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.
  7. The wiring diagram will also show you if there are start and run capacitors on your AC. Either of these could be bad and need replacing.
  8. Disconnect the thermostat at the wall and if possible, disconnect the wire and reattach it again. Also, reset the thermostat by following the steps outlined in the user manual.

Quick Reference RV A/C Fan Troubleshooting Table

A/C Fan SymptomsTesting ProcedureHow To Fix
A/C fan won’t stop runningCheck compressor and capacitors    Replace or repair the compressor  
A/C fan repeatedly turns on and off Check that capacitors are working  Replace capacitor/ Check power flow to the unit
A/C fan won’t turn on at allCheck if breakers are tripped Ensure power flow to the unit
The compressor won’t turn on, but the fan doesCheck for a bad thermostat Replace thermostat, control board   
A/C fan speed is inconsistentTest motor voltage/check for debrisReplace motor voltage, clean unit 
A/C fan makes an unusual noise, like whistling or scraping Remove shroud, check for interference with the motors Remove debris, test capacitors, and compressors 
A/C fan makes a humming noise but won’t turnCheck for damaged compressor, coils, capacitors, voltage  Replace capacitors, clean coils, compressor
Airflow at the vent is very weakCheck the unit for dirt or leaves Clean the condenser coil/clean components coils, evaporators, etc. 
Airflow from the A/C is not coldCheck the fan motor  Clean or replace the fan motor 

Checking the AC unit on the Roof Of Your RV

If at this point your AC still hasn’t started, then get up on the roof of your RV for additional inspection and tests.

But first off, if you’re not in a position to get up on the roof safely, then don’t attempt it. Have someone else do it for you.

Electrical inspection:

  • When you get to the roof, unhook the AC shroud to reveal the electrical elements and motor.
  • If the motor is getting any power, you should read it from your voltmeter; and the meter will also tell you whether the power registers within the proper amperage.
  • Also use the voltmeter to check for continuity in case of higher-than-normal amperage. So if the wires are corroded at any point and the connections you could see this. It may be necessary to open them up and redo every connection, going back to the circuit breakers.

Working on the control board:

  • Pop open the access panel to inspect the control board – which is right under the AC shroud.
  • Determine which of the wires out of the control board are burned, disconnected, or just loose.
  • The control board components should not be burned or discolored in any way. Nor should there be a strong smell of burned plastic.
  • Check that the insulation 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.
  • An expert at a repair shop should repair any severe damage to your control board.
  • How is the thermistor working? To find out, use your voltmeter by attaching it to the thermistor lead and heat the copper to see whether there will be a reduction in resistance. If yes, this means that the thermistor is in good working condition.
  • At this point, if the AC still won’t work, you can move on to check the condition of the relays and capacitors, although this might mean getting into more technical aspects of the job.

What Causes An A/C Fan To Stop Working?

There are two main types of RV roof AC.

  • 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 consists of an AC unit’s technical inner workings: Which include a condenser, compressor, and evaporator.
    It’s not uncommon for a camper to step out of the RV for a short time and, when they get back, find that the air conditioning fails to cool. If this happens, you may diagnose and fix the problem by identifying which of these problems is affecting your AC.
  • The AC unit is old. After years of use, even the best AC units won’t cool as well.
  • Temperatures outside are scorching. If it gets too hot out, the AC may struggle to keep up – which might feel like it’s not working.
  • The fins, coils, and air filters have not been cleaned for a long time, and they’ve collected a lot of dirt. It is a common cause of AC failure, so check that your unit hasn’t collected a ton of grime affecting airflow.

Diagnosing Your AC Fan

The following are common RV AC problems that will help you identify why your unit isn’t working.

  1. If a strange noise comes out of the unit when it powers on, that might indicate that some of the controls and units are not receiving enough power.
  2. If the AC fan fails to start, is slow to start, blows warm air, or keeps tripping your circuit breaker, there’s probably something wrong with the capacitors.
  3. If the AC only works when the thermostat wires are connected, the thermostat is likely broken, so have it replaced.
  4. If the AC is not working, but the control board is okay, replace the fan motor or compressor; or both.
  5. If the unit overheats, replace or clean the coils.
  6. If water leaks out of the AC unit, it could be condensing in a place where the fan can’t reach it to turn it into moisture. Cleaning the coils will fix this.

RV AC unit Humming but Fan not Running

Sometimes you will turn on the AC unit and you will hear it humming but the fan is not running. What is that all about?

If the RV AC unit is humming or buzzing but the fan is not running there may not be enough amps for the unit to start up or you may have a faulty fan capacitor or start capacitor. Alternatively, the fan or blad may simply be stuck and unable to turn.

Make sure you have enough amps from your power source. If you are plugged into the 30 or 50 amp outlet that your RV requires. Also, check that your extension cord is not too long and the correct gauge wire.

If the fan is stuck it will be difficult to rotate by hand. Looking at it you can figure out of a blade is bent or stuck. It may also just be jammed or gunked up from sitting over the off-season. A gentle nudge will get it going again.

A faulty fan start-up capacitor is cheap and easy to install. Cut the power, open the AC unto, 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.

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 Your RV A/C Fan

Is your AC showing signs of freeze up, leaking, or clogging? To avoid this type of problem, your AC requires regular maintenance. Here are tips on cleaning your RV AC unit:

  • To prevent injury, unplug the unit before the cleaning starts.
  • Start with the filter: If your unit finds regular use, clean the filters every few weeks with warm water.
  • Let them dry out and if torn or damaged, replace them.
  • Clean the evaporator coils: Once you get the unit’s filters, 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.

To keep the AC in top condition, follow these tips:

  1. 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, which is why, whenever possible, leave the thermostat set at “on,” so the temperature will adjust itself automatically.
  2. Use the roof vent instead of AC where possible. It should keep the AC in good condition.
  3. Oil the AC fan regularly to keep it working in perfect condition. (Pro tip: use mechanical oil, not WD40)
  4. When the RV is not in use, keep the AC unit covered up to prevent damage and the usual wear and tear.
  5. The condenser coil accumulates dirt, and you must remove this now and then to keep airflow uninterrupted.

Here are more articles that you might be interested too:

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    Shauna Kocman founder of Family Travel Fever

    Hi, I’m Shauna – Welcome to Family Travel Fever.  We are a large family, that was bitten by the travel bug!  We travel with kids and extended family.  I take the kids by myself sometimes because I don’t mind flying or driving solo with my crew to discover the coolest places.

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