Adding Second AC to 50 Amp RV: A Complete DIY Guide

Your 50-amp RV can run two ACs simultaneously. However, some vehicles might not be properly wired for the second unit. Moreover, faulty installation can hinder the performance of the first AC. 

Adding a second unit starts with selecting an unobstructed spot on the roof. If the RV doesn’t have one, you must install new wiring and circuits for the unit. Lastly, put in a circuit breaker, thermostat, and power switch for the new unit. 

A second AC unit can greatly increase the comfort of your RV. Meanwhile, improper installation can make it a burden. Follow this discussion for proper guidelines.

Adding Second AC to 50 Amp RV

Can You Add a Second AC to Your 50 Amp RV?

It is possible to add a second AC to your 50-amp RV. But first, you must ensure the compatibility of the unit you plan to install. You should consider how this second addition would affect your surroundings. 

Roof and Height Clearance

You can add a second AC to your RV if the roof supports it. For instance, the installation would be risky if the unit is too heavy for the roof. The same is true for a medium-sized unit but an old and battered roof. 

The AC unit shouldn’t exceed the height clearance for your RV. Otherwise, you couldn’t drive safely beneath bridges, trees, powerlines and overpasses. It can also get you in trouble with the law. 

Electrical Compatibility

There are many RVs wired only for a single AC unit. If your RV has a similar arrangement, you can’t add a second unit without modifying it. 

The owner’s manual can tell if the RV is wired for a second unit. You might also find ‘AC Ready’ panels and connectors on the roof. Otherwise, you must get an electrician to install new wiring and circuit for the second AC.

Does your RV have a duct system? In that case, you may need to extend or modify it to adjust the system with the new AC. 

Lastly, the campgrounds where you park your RV must be able to provide 50 amp shore power. And, of course, the RV itself should have a 50 amp plug.

Read Also: RV AC Freeze Sensor Location [Complete Guide to a Freeze Sensor]

Consumption and Capacity

Adding a second unit will significantly increase the energy consumption of your RV. This might affect the performance of other electrical appliances, such as your microwave, water heater and the first AC.  

You can choose an AC unit with a High Energy Efficiency Ratio and Low Start-up current in this situation. 

To ensure optimum cooling, pick an AC with proper British Thermal Units. The retailer should be able to advise you on this.

For instance, an AC with 15000 BTU can effectively cool 750 square feet of RV space. This is merely for reference, and you should factor in the capacity of the first AC when making this calculation. 

Noise and Vibration

Your second AC will create noise and vibration when you run it. The aim is to minimize it as much as possible so it doesn’t disturb your campground neighbors’ peace. 

So, try to install a unit that has a low decibel rating. You can also use some rubber pads and insulation to contain the vibration.

Read Also: 6 Reasons Why Does RV AC Compressor Start and Then Stop

A DIY Guide to Adding a Second AC to Your 50 Amp RV

So, you have confirmed your RV can handle a second unit. Now, it’s time to start the installation process. It can be a one-man job if you have sufficient experience. Otherwise, keep an assistant for safety. 

Step 01: Preparation

You must clean the RV roof properly before installing the unit. Also, choose a spot that is free from any obstruction. 

Ensure you have all the necessary tools at hand. These include a tape measure, a marker, a driller, screws and the AC unit itself. 

Be careful when lifting the unit on the roof. It’s best to have someone present to help you with the lift. 

Step 02: Cutting the Hole

If your RV’s roof has a hole for a second AC unit, it will save you some trouble. Some roofs don’t have a hole but an appropriate vent system. 

However, many RVs don’t have a roof hole exclusively for an AC unit. In that case, you have to make some modifications.

First, get your owner manuals and check the roof’s diagram. Ensure no important pipes or wiring passes along the space you will cut through.

Mark the dimensions of the AC on your roof with a tape measure and marker. Then, start cutting the hole.

Read Also: RV AC Unit Humming But Fan Not Running – Why & How To Fix?

Step 03: Mounting the Unit

Most of the RV ACs divide into a base and a top. The base goes inside the RV and connects to the ceiling assembly. Meanwhile, the top stays outside and contains the compressor, condenser, and fan. 

Install the AC Unit Base on the hole. Ensure proper leveling and alignment of the base. Use screws to fit the base securely on the hole. Apply sealant where the borders of the AC base and the hole meet. 

Next, attach the top part to the base. The two parts of the AC unit are supposed to fit seamlessly. So, you shouldn’t have much trouble with this. Also, check the AC unit’s instruction manual before starting. 

Step 04: Connecting the Wirings

You have to connect the wirings after installing the AC. This step requires wire strippers, electrical tape, and wire nuts. 

Find the second AC prewiring or the one you installed recently. It’s near the vent or ceiling assembly. 

Connect the AC and RV wires by matching them according to the color code. The wire strippers can help you cut and pull off insulation. Use the wire nuts and electrical tape to secure the connections. 

Find the power control panel of your RV. Install a 20 amp circuit breaker for the new unit. Label it to distinguish it from the first AC’s circuit breaker. 

You should also install a power switch and thermostat for the AC unit. These parts have clearly marked wires and relevant instructions to connect with respective AC wirings. So it shouldn’t be much of a hassle. 

Lastly, check for any exposed wires and trim or cover them up.

Read Also: How to Solve RV AC Clicks But Won’t Turn On Problem?

Step 05: Test Your Unit

Do a little testing to see if your unit is running well. At first, you have to turn the breaker on. If there is a problem along the connections you have made, you will see sparks or noises from the breaker panel. 

Now turn the main switch on. Your AC should start running immediately. Notice if there is any vibration or abnormal sounds from the unit.

Excessive vibration tells you there might be loose screws where the AC base connects with the hole. Also, check the vents connecting to the second AC for proper airflow. 

If your AC is running well, check the thermostat. Set it to your preferred temperature and mode. Expect the AC to cool or heat the RV according to your setting. A compatible thermostat should’ve no issue with this.

Read Also: RV AC Soft Start Vs Easy Start Kit | Which One is Worth it?

Some Safety Tips on Installing an AC on an RV

Adding a second AC to your RV is challenging. Especially when you aren’t a professional at it. Here are some things you can keep in mind for a safe and flawless AC installation- 

  • Disconnect your RV from shore power when working with exposed wires.
  • Wear goggles and other protective clothing to protect yourself from projectiles, electric shocks, etc. 
  • Use ladders, harnesses, and scaffolds (as necessary) to work on the roof safely. 
  • Properly seal the gaps between the hole and the AC unit to prevent the escape of heat or cold. 
  • Don’t start the AC installation on a day with bad weather.


Hopefully, you now know enough to install a second AC on your RV. Have more queries. Feel free to ask here- 

Will adding a second AC on my 50 amp RV affect the other appliances?

A 50-amp RV has the required capacity to support two ACs.  So, you won’t generally experience any problems. However, you must balance the appliances between the two legs of the 50-amp service. Otherwise, you will trip the breaker. 

How will adding a second AC on the roof affect my RV’s Aerodynamics?

An AC unit on the roof can increase the RV’s wind and drag resistance. As a result, your RV will slow down and have difficulty maintaining speed. So, choose an AC unit with a stream-lined aerodynamic design. 

How often should I replace the air filter of my RV’s AC?

Your RV AC unit has three filters- the engine, cabin, and AC unit filter. The engine air filter requires changing after 12-15000 miles or one year of use. You can use the cabin filter for two years. The AC unit needs replacement after 150-400 hours of use. 

Final Words

Adding a second unit to your 50-amp RV can make things more comfortable. 

However, you must balance the two units between the two legs of the 50-amp service to prevent short circuits. 

Also, prioritize personal safety when working alone on the DIY AC installation.

Read Also: Ducted vs. Non-Ducted RV AC: What Should Be Your Choice?

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