RV Air Conditioner Troubleshooting Guide (DIY Tips)

RV air conditioners are a must-have when camping during hot summer months. While they are dependable, spending time in your RV can be uncomfortable when it’s not functioning correctly. Below are a few common problems and troubleshooting tips for dealing with a non-functioning or poorly performing RV air conditioner.

Most RVs will have a rooftop AC unit (or two) that pulls air from the interior of the RV, cools it down, and circulates the cold air through roof vents in your RV. With proper maintenance, your RV AC unit will last many years. However, since there are many components of the RV cooling system, diagnosing issues can seem challenging. Below, we’ll cover some of the more common issues and suggest solutions. However, remember that if it’s a really hot day, it’s possible that your AC unit is not powerful enough to keep things as cool as you want.

Since the air conditioner may be hard to access, it’s a good idea to write down the model number of your unit and keep it handy if you need to order parts or look up an electrical diagram.

My air conditioner is not turning on!

Is the thermostat set correctly?

If your air conditioner is not turning on, the first thing to check is the thermostat and electrical connection. On your thermostat, make sure that it is set to cool, and the temperature is set below the current ambient temperature in the RV. The air conditioner will only turn on when the temperature in your RV rises above the set temperature.

While it may seem silly, almost every RVer will experience what they perceive to be a non-functioning air conditioner, only to realize that they still have the thermostat setting switched to heat. So if you’re having problems with your air conditioner, check this first since it can be easy to overlook.

Is the air conditioner getting power?

In addition to testing the air conditioner for cooling, try it on fan mode. If the Air conditioner operates with just the fan, you know that the AC is receiving power. Of course, you’ll also want to make sure the thermostat is selected to cool and not just on fan mode. But, again, this is easy to miss.

The part of the air conditioner that does the cooling is the compressor. If it’s getting power, but the compressor doesn’t run, it’s time to check a few more things. There can be a few things causing problems, including the thermostat and the air conditioner itself. If no power is getting to the air conditioner and the fans don’t run, you likely have an electrical issue or problem with the air conditioner unit.

Is there an electric problem?

If all is good with the thermostat settings and your fan is working, but it’s not cooling, you may need to do some thermostat troubleshooting. However, if nothing is working, it’s time to check your electrical connections. First, make sure that you’re fully connected to shore power. If you are, and everything else in the RV is running (microwave, power outlets, etc.), check the breaker panel and find the breaker for the air conditioner. Make sure that you don’t have a tripped breaker. If power is out for other appliances, you may have a problem with your shore power.

Ensure that your RV is connected correctly at the post and to your RV. Also, check the breaker in your RV and on the breaker for the pedestal outside. Now is also a good time to meet your neighbor and ask if they have any electrical issues. During hot summer months, when everyone is running their air conditioners, it’s not uncommon for the campground to have a power outage. It’s easy to lose shore power and not notice it because your 12-volt appliances will still run off the battery. However, you wouldn’t be the first person not to notice.

If you don’t find any issues with the shore power connection, the next two things that you will want to troubleshoot are your thermostat and the air conditioner. Let’s start with the thermostat:

Diagnose a faulty thermostat:

One of the most common reasons that your air conditioner compressor doesn’t turn on is a problem with the thermostat or control board. Thermostats can malfunction due to old wiring, dust buildup, and a loose wire connection. Another common issue is that the thermostat cannot read the ambient room temperature, which prevents it from engaging the compressor. A simple test that you can do to see if you have a thermostat issue or something else is to turn on the heat. Set the thermostat higher than room temperature and see if the heat kicks on. If it doesn’t, you may have a faulty thermostat. If it cannot read the room temperature, it won’t engage the HVAC appliances. You’ll likely need to replace the thermostat.

If you do not see any display readings on the thermostat, it’s not getting power. While less common, some RV thermostats run off a battery. If yours does, simply replacing the battery may solve your problem. If not, it’s time to disconnect the thermostat from the wall and inspect the wiring. Check for loose connections, damaged wires, or dust buildup. If you find any of this, clean or repair the connection and retest. If this doesn’t work, it may be time to replace the thermostat.

Diagnose problems with the Air Conditioning Unit

If the thermostat appears to be working, the next step is to inspect the air conditioner. Several things can malfunction on the air conditioner, and unfortunately, many of the repairs are not a DIY job. For example, if your air conditioner works intermittently and you hear the compressor trying to start, or it starts and stops, you likely have an electrical problem or issue with one of its components.

The air conditioner Is not blowing air

Follow the steps above and ensure that you have power getting to the air conditioner and thermostat. A bad thermostat can cause this problem, but you will need to check the air conditioning unit if it’s functioning correctly.

If your air conditioner is not blowing air, you may have a bad fan blower motor even though you may hear the compressor running. This repair can be a DIY job if you’re handy and experienced working around electrical components. You should also check your fan’s capacitor. A bad capacitor can also cause the fan to stop working.

Does your air conditioner work and then stop soon after?

If your RV air conditioner is short cycling, you may have dirty coils. Dirty evaporator coils are a common problem for air conditioners that overheat or won’t stay running or are dripping water. The good news is that you can have your coils cleaned or even do it yourself if you feel comfortable accessing the AC. Cleaning the coils is not difficult, but you will need to get on your RV roof and remove the air conditioner cover.

When servicing it, always ensure that the power is off to the air conditioner. When removing the AC cover, take a plastic bag and cover the electrical connections to prevent moisture from getting on them. You can buy evaporator coil cleaner spray at most RV stores or online. Following the product’s instructions, most will require you to spray the coils, let them sit for 15-20 minutes, and then rinse them off with a garden hose. Use a gentle spray when rinsing. If your condenser coils are very dirty, you may need to repeat this process several times.

This problem can also indicate a bad capacitor. A telltale sign of a bad capacitor is a humming noise coming from your AC as it tries to start. Both the fan and compressor have capacitors. Another sign of a bad capacitor is when your unit starts but trips the circuit breaker.

The air conditioner compressor does not turn on.

If your air conditioner is blowing warm air and the compressor isn’t turning on, you likely have a problem with the RV AC compressor or the start capacitor. More common is a bad capacitor, which is easy to fix. However, if your compressor is causing the problem, you may need to purchase a new RV air conditioner.

While you can replace the capacitors yourself, it’s best to hire a professional if this is outside of your comfort zone. Even when powered off, capacitors will still hold electricity, and you need to discharge them before servicing.

Replacing the compressor is often not cost-effective, especially if your AC is older. This repair is a job for a professional if you need to replace it. However, most compressor-related problems are often from the capacitor and not the compressor itself.

The other thing to remember is that you may not have enough shore power to run your AC. This situation is especially true if you have multiple AC units and your RV is connected to a 30A hookup. It’s very likely that your AC unit is not getting sufficient power to start it, especially if both are running simultaneously. RV air conditioners require more power at startup and less power during normal operation. You can add hard start capacitors to help make sure that both units have enough power to run.

My RV air conditioner is very noisy.

While your air conditioner may be experiencing a problem, a common cause of the noise is when something interferes with the fan motor. It’s possible that debris got under the shroud or a part of the air conditioner unit detached and is hitting the motors. Many air conditioners will also have rubber shock absorbers. Sometimes they can dislodge and contact the compressor coils or fan. To troubleshoot the noise, you’ll need to get on the roof, remove the shroud, and inspect the area around the motors for obstructions. If there are obstructions, you will want to inspect and adjust them so they don’t contact the moving parts.

Ice buildup or very cold

If your air conditioner is very cold and you notice ice buildup, you may be low on freon. This issue will eventually cause your air conditioner to stop cooling. You can buy Freon fill kits for some units. These kits will require you to tap into your freon line and replenish it. While some units may allow an easy top off, others may require the help of an RV technician. While this may solve the problem, you should also inspect your coils for freon leaks and repair them if found. A leak is easily found by looking for visible oily residue on the copper tubing.

Your air conditioner is not cooling my RV.

If your AC is running but isn’t getting cool enough, there are a few things to check. First, remember that in hot weather, especially if it’s really hot outside, your AC may be struggling to keep up and cool down your RV. If this is the case, you can do a few things to make your RV more efficient. An easy first step is to close your blinds. You can also insulate your windows to keep the cool air inside and the hot air outside. You can also insert insulation into your ceiling vents, such as a Camco insulation pillow.

The other thing to check is your AC air filter. You’ll find removable filters on rooftop air conditioners. The filters are located on the inside panel on your ceiling and can easily get covered in dust. A dirty air filter can choke out the cooling capacity of your ac system. These air filters are removable and can usually be washed in the sink. By cleaning the filters, you will allow more fresh air into the AC, which will significantly improve the efficiency of your unit. Cleaning the filters should be part of your regular maintenance schedule for your RV.

You may also need to replenish your Freon, which you can easily do yourself for most RV air conditioners. Always make sure that you’re adding the correct coolant for your air conditioner model and following instructions.

Conclusion

Troubleshooting a non-functioning RV air conditioner may seem challenging at first, but with a little bit of know-how, you can identify and solve many problems on your own. Most RV rooftop units are fairly similar and utilize many of the same types of components. If your cooling unit is not working, the best way to solve it is to take a closer look at the individual components necessary for it to operate correctly. Some issues can be easily and quickly remedied using basic tools, such as a blown fuse, poor airflow, and a dirty filter. Other problems may require a little know-how or an RV air conditioner repair technician. By following some of the troubleshooting steps above, most RV owners can figure out what’s needed to get their unit blowing cooler air.

2 thoughts on “RV Air Conditioner Troubleshooting Guide (DIY Tips)”

    • Sounds frustrating- I would venture to guess that something is hitting something inside your unit. Your fan may be out of balance and making a knocking noise. Another possibility is that the compressor has loosened up and moving around. Do you have the ability to get on the roof and inspect it?

      Reply

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