Do You Need an RV Air Conditioner Soft Start?


Conner Lund

Favorite Trip

Backpacking Ozark Trail

Home Base

Bowling Green, KY

Favorite RV

Winnebago Revel

About Contributor

Conner Lund is a Technical Content Writer. He has both hands-on experience and real-world knowledge. He’s an avid outdoorsman: camping, hiking, backpacking, mountain biking, kayaking, hunting, and fishing are all things he enjoys that you could find him doing on any given weekend. He loves to travel and see new places. He does most of his exploring and camping out of his overlanding truck with a rooftop tent.

With improvements in RV solar charging systems and increased availability of portable generators, RVers are no longer limited by campground availability. But when you aren’t plugged into a shore power pedestal (and even sometimes when you are), you may not have sufficient power to start your air conditioner. That’s where an RV air conditioner soft start makes a huge difference. 

Some manufacturers now install soft starts in their air conditioning units at the factory. If your camper doesn’t have one, adding one can improve your ability to start your A/C when generator or shore power is insufficient. Let’s explore how an A/C soft start works, why you might need one, and how to install one in your RV. 

What Is A Soft Start for RV Air Conditioner?

Coleman Mach RV AC with soft start
Photo by Coleman Mach

A soft start is a device installed in your air conditioner to reduce start-up power requirements. They are typically mounted inside the roof-mounted unit under the A/C shroud, but some also plug into the shore power pedestal.

How Does an RV A/C Soft Start Work?

Amp graph of AC soft start
Photo by SoftStartRV

An RV air conditioner soft start is installed in line with the compressor that powers your air conditioner. This device limits the compressor’s initial power surge. Instead, it slowly pushes power to the motor until enough is achieved for startup. Without a soft start, a large surge of power is sent simultaneously, causing more strain on the camper’s electrical system.

Every RV air conditioner has two important power ratings: starting and running. The starting requirements are how much power the unit needs to power on, and the running requirements are how much power it needs to stay running. 

The starting requirements are much higher than the running requirements. A lower starting power requirement makes it easier to power up, putting less strain on your electrical system and reducing wear and tear on the compressor. These requirements are listed as “watts” or “amps.” Using an online calculator, you can easily convert watts to amps or amps to watts if needed. 

Why You Need an RV A/C Soft Start

Inside view of soft start installed
Photo by SoftStartRV

There are many benefits of using a soft start on your RV’s air conditioner and a few reasons not to. Let’s take a closer look at these below. 

Off-Grid Use

One reason to add a soft start to your A/C is because you like camping off-grid using a generator. Generators allow you to explore more and avoid crowded campgrounds. 

The problem with running your air conditioner off generator power is the large amount of power these air conditioners require during start-up. At the minimum, you’d need a 3,500-watt generator to power one 13,500-BTU RV air conditioner. In cases where you have a 15,000-BTU unit or multiple air conditioners, the generator sizing can double. The more power your generator offers, the more expensive and physically larger it will be.

Adding an aircon soft starter can reduce your air conditioner’s starting power requirements by up to 70%, allowing you to use a much more cost-effective and physically smaller generator.

Technician Tip: As the industry changes rapidly, watch for DC air conditioners and digital A/Cs that run on inverter power (from your batteries). A soft start is often required for these units and is typically installed at the supply side near the battery bank.

Start-Up Noise

If you’re a light sleeper, you’ve probably been awoken by the air conditioner booting up in the middle of the night. This is especially true if you have an A/C unit directly above your bed. A soft start reduces the noise an air conditioner makes during start-up, allowing you to sleep more peacefully.

Technician Tip: A soft start won’t reduce a unit’s noise level while running.

Wear and Tear

By limiting voltage spikes to the compressor during start-up, an RV A/C soft start reduces wear and tear on your cooling system over time. The less wear and tear you have, the more reliable it will be and the longer it will last. In other words, a soft start can save you money by extending the life of your system and reducing the frequency of replacements.

Shore Power

A soft start isn’t exclusively for generator use; you’ll also benefit from using one at the campground or when plugging into power at home. For example, if you have a camper with multiple air conditioners and the park only offers a 30 amp service, you may not be able to run both units due to the high start-up demands. 

However, with a soft start, you’ll reduce the total starting requirements, increasing your chances of powering both units simultaneously. When camping at a metered location where you pay for electricity separately from your site rental, an A/C soft start eliminates surges to the grid power system that drive up your electric bill.

Technician Tip: A soft start is installed onto a single air conditioner; if you have multiple, you must purchase a separate soft start for each one. 

Downsides of Using an RV Air Conditioner Soft Start

If you’re wondering about the downsides of using a soft start for your air conditioner, there aren’t many. However, they can be expensive, and if hardwired into your air conditioner, they may require professional installation, which is another expense. It’s also important to add that they won’t necessarily reduce your overall power demands, so don’t expect much savings here. 

Is a Soft Start for RV A/C Worth It?

Although admission is expensive—most range from $200 to $400—a soft start is worth it for off-grid campers using a generator or those with multiple air conditioning units. If you only stay at campgrounds with dedicated 50-amp service, you might not find as much value in a soft start air conditioner. For everyone else, they are absolutely worth the money. 

How To Install a Soft Start for an RV Air Conditioner

Photo by SoftStartRV wiring diagram
Photo by SoftStartRV

Although an A/C soft start kit can plug into the shore power pedestal, most must be wired into the air conditioner. To hardwire your A/C soft start, you’ll need a few tools. Let’s review these below.

  • Screwdriver (Hardware varies by manufacturer)
  • Wire Strippers
  • Wire Crimper
  • Electric Tape
  • Test Light or Multimeter

Once you have the correct tools, you can begin installation. 

Technician Tip: Always refer to the installation instructions for specific steps and wiring instructions. If you don’t feel comfortable completing the installation yourself, contact one of our local service centers. 

You can use these general tips and practices for most installations. 

  1. Turn off the breaker and unplug shore power.
  2. Ascend to the RV roof and remove the air conditioner shroud.
  3. Identify and locate the compressor and start capacitor (cover panels may need to be removed to access these components).
  4. Locate the air conditioner’s model number and obtain the wiring diagram from the soft start manufacturer.
  5. Attach wires from the soft start to the compressor and start capacitor.
  6. Use electrical tape to seal all connections.
  7. Mount the soft start inside the overhead unit with the connector facing down, clear of other components.
  8. Reinstall cover panels and overhead shroud.
  9. Apply power to the breaker.
  10. Check for proper operation.

Technician Safety Tips

Use this safety advice from our expert technical service team to stay safe during this installation. 

  • Discharge the existing start/run capacitors before installing to reduce the chances of electric shock.
  • Never work on high voltage alone.
  • Utilize fall protection anytime you are working on elevated surfaces.
  • Consider insulated tools or dielectric gloves to reduce the risk of electrical shock.
  • Check for insect nests before removing the A/C shroud.

At the end of the day, it all comes down to how you use your RV. If you boondock or have an RV with multiple large air conditioners, an A/C soft start can dramatically increase where you can camp and how comfortable you can keep your RV’s climate during your stay! 

Let us know in the comments below if you have a soft start kit and how you like it. 

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