How to Troubleshoot Your RV Air Conditioner

Maybe your RV air conditioner is more a toasty trickle than a refreshingly cool breeze. Or maybe you're experiencing leaks, or the air conditioning smells worse than the kids' dirty socks.

Whatever the problem, many common RV AC issues have relatively simple fixes. Check out our troubleshooting guide below for help getting your AC up and running normally again, so you can enjoy an RV that feels less like a sauna and more like the home away from home it's meant to be.

Disclaimer: The following is intended as a general guide for troubleshooting common RV air conditioner issues. This is by no means a comprehensive list of every problem you may encounter, nor can we provide diagnostic or technical assistance for your specific AC unit. Although many common issues can be remedied at home, when in doubt, it's always best to bring your RV to your local professionals.

Warning: ALWAYS disconnect the AC from its power source prior to servicing it. Make sure not to touch capacitor terminals with your bare hands, even after disconnecting the power. The capacitor can still hold a charge even after disconnecting and must be discharged before handling.

RV Air Conditioner Components: What You'll Find "Beneath the Hood"

Before we begin, it helps to have a basic grasp of the components found on an RV air conditioner. Here are a few you'll run into:

COMPRESSOR: Compresses the vapor refrigerant (such as Freon) and heats it before the vapor travels to the condenser.

CONDENSER: Cools the vapor and condenses it into a liquid. The condenser can be seen from the rooftop after removing the AC shroud.

EVAPORATOR: Changes liquid into a superheated vapor. The vapor is pulled into the compressor, and the cycle begins again. You can usually see the evaporator from inside the RV when the filter is removed.

FANS & MOTOR: One fan moves air across the condenser. A second fan moves air across the evaporator. The fans and motor can be accessed from the camper rooftop after removing the shroud.

CAPACITORS: (Motor run and motor start capacitor.) Provide a high voltage charge to the fan motor and compressor. The capacitors can be accessed from the rooftop after removing the shroud. Capacitors may still be charged even after shutting off the power, so make sure not to touch the terminals with your bare hands, even after disconnecting the power. Use a capacitor discharge tool to safely dissipate any remaining charge prior to servicing the unit.

RV Air Conditioner - Top View

RV Air Conditioner - Side View

Pro tip: When disassembling your AC unit, take a picture first so you can easily reassemble it.

How Does an RV Air Conditioner Work? - Diagram

RV Air Conditioner - Side View of Fan and Motor

How to Troubleshoot an RV Air Conditioner

None of us enjoy camping in an RV that feels like a sauna. Luckily, if your AC is malfunctioning, it could very well be a common problem with a relatively easy fix. Check out the list below for a list of common RV AC issues and what to do about them.

RV AC Power Issues

1. Why Won't My AC Turn On?

Make sure your RV power supply is functioning properly by plugging something into an outlet. Also check the breaker and make sure you didn't trip it.

2. Why Does My RV AC Trip the Breaker?

If you're not overloading the circuit, then the issue is likely dirty components, a bad compressor, or a bad capacitor. Complete the above maintenance steps and clean your unit thoroughly. If this doesn't help, use a multimeter to test your compressor and capacitors.

3. Why Does My AC Compressor Kick On and Off?

The issue could be a bad thermostat or control board, both of which can be checked by a local professional. This might also be caused by a weak capacitor (which is inexpensive to replace) or a frozen evaporator coil, in which case you can run your fan on high (not cool) until it unfreezes.

4. Why is My RV AC Freezing Up?

If your AC "freezes up" and stops working on a hot day, it could be dirty or "frozen" with accumulated ice. Perform the maintenance steps listed above—clean your filter, condenser coils, and evaporator coils. In particular, check your evaporator coil for ice buildup. If ice buildup exists, run your fan on high (not cool) until it unfreezes.

In rarer cases, you could have a refrigerant leak. Because RV ACs are sealed units and are not easily recharged, it's best to take your RV to the pros to recharge your AC with refrigerant. In some instances, it may be more cost-effective to simply replace the unit.

Troubleshooting RV Air Conditioner Power Issues - Flow Chart

RV AC Airflow Issues

1. Why Is My RV AC Not Blowing Cold Air?

If your AC has always kept your camper as frosty as the north pole but suddenly can't take the heat, first complete the maintenance suggestions above. It's possible your filter or coils just need a quick cleaning.

If the AC fails to blow out air at all, check your fan motor to make sure it's working properly. Clean or oil it as needed. If your AC blows only hot air, it may be a problem with your compressor. You can test the compressor with a multimeter. If the compressor is bad, it's typically more cost-effective to simply replace the AC unit altogether.

Also check your capacitors by testing them with a multimeter (after discharging them). What can seem like an issue with the fan or compressor can often be easily fixed with a new capacitor.

If your AC has never been able to keep up during particularly hot days, you may just need a second AC unit to cool your entire RV.

2. Why is My RV AC's Airflow Weak?

You may have a clogged component somewhere in your system. Start by checking your filter, evaporator coils, and condenser coils and cleaning them if necessary. Check your evaporator coil for ice buildup. If ice is present, run your fan on high (not cool) until it unfreezes.

Also check for leaks or holes in your vents and ducts. Reseal any holes using metal tape and strip caulking. (Do not use duct tape—it won't last.)

The issue might also be related to the construction of your RV's duct and vent system. If your RV is under warranty, your local RV dealer may be able to help with the problem. Some RVers also use DIY fixes. For instance, enlarging their vent openings by removing the AC cover inside the RV, then using tools to cut away a fraction of the aluminum framing and styrofoam insulation. Another modification (particularly on Keystone motorhomes), is to use styrofoam and foil tape to block off the "excess duct" that travels several feet beyond the vents. This "dead space" allows for the collection of cold air in the duct, rather than forcing it to flow into the RV's interior living space.

Although we are big proponents of the DIY spirit here at etrailer, we always recommend consulting with your local professionals before attempting any modifications to your RV.

3. Why Does My RV's Heat Not Keep Me Warm?

Keep in mind that ACs with heat pumps typically aren't built to keep your unit warm in temperatures below about 45 degrees Fahrenheit. This is because heat pumps essentially work the opposite way of an AC. That is, they draw heat from outside and use it to heat your rig.

Of course, you can see how this becomes a problem in colder temperatures, where there's not enough heat to draw from outside. Your heat pump is perfect for a cool fall evening, but when it comes to the more frigid temps, you'll you'll need to run your propane furnace.

Also, don't mistake your heat strip for a heat pump. Heat strips are designed to provide a heat boost, much like a RV space heater (which is another option for battling cool—but not frigid— temperatures). Heat strips are not meant to heat your whole RV like a furnace.

Troubleshooting RV Air Conditioner Airflow Issues - Flow Chart

Other RV AC Issues: AC is Loud, Leaks, or Reeks

1. How Can I Make My AC Quieter?

If you're suddenly experiencing more AC noise than before, remove the shroud and check if anything is interfering with the motors. Also make sure the shroud is secure on the roof and does not allow for excess vibration. Test the compressor and capacitors with a multimeter to make sure they're functioning properly.

Some AC models are also simply louder than others. There are aftermarket noise reducers available for RV ACs that may work for you.

2. Why is My RV AC Leaking Water?

Check the drain pan to make sure it's not clogged, and clean it if necessary. Also clean your evaporator coil if needed. Check to make sure the mounting bolts aren't loose and the gasket is snugly (but not too tightly) secured on top of your RV.

3. Why Does My RV AC Unit Smell Musty?

Musty, mildewy smells can result from clogged or dirty components in your AC unit. First, complete the maintenance steps mentioned above if you have not done so recently and clean your filter and evaporator coils. You should also check the evaporator drain pan for clogs, which can cause water to back up and become stagnant (and therefore smelly).

If the smell is more akin to something rotten, check that no critters have holed up and died in your AC unit. If the smell comes from a specific vent, check the duct for dead critters. Otherwise, a propane leak or overcharged house batteries can give off a rotten smell that is then circulated by the AC.