Soft Start RV AC Guide

What Is Soft Start For RV AC Units?

No one wants to stay in an RV during a hot summer without an AC. The issue is that the RV AC draws a lot of current when it starts up, that’s just how they are designed. Once the AC is running, the current draw drops significantly, but the startup is a really hard draw.

The Soft Start is a device that reduces this hard current draw significantly.

Soft Start RV AC explains it like this: “A soft start for RV AC is technology that lowers the initial power draw used by your air conditioner’s compressor. You install these small electronic devices directly onto the compressor, and they directly modify the startup process to prevent issues related to the current spike when a compressor kicks on.” (Source:

Not only does this help with the overall current draw management, but it also help the AC unit last longer and be less “abused” by the constant high current draw during start-ups. This is because the hard start causes the inrush of current during the start to be heightened which can put your motor at risk of overheating or suffering a shorter lifespan.

How Does An RV AC Soft Start Work? again does a good job explaining how a Soft Start works: “Compressors for air conditioners draw a tremendous amount of current at start-up, something inherent to larger AC motors. This is called the startup current.

A soft start connects to the air conditioner’s compressor and modifies how it operates when it turns on. Instead of drawing as much power as possible instantly, a soft start will gradually increase the power draw until the air conditioner’s compressor fully kicks on.

This slight difference removes the problematic current spike that can overload the power system of the RV.” (Source:

So how does a soft start capacitor work? “A soft starter works by controlling the amount of voltage running through the circuits of a motor. The soft starter can do this by affecting the torque of a motor, which reduces the voltage and allows it to manipulate the voltage to allow for a smooth startup and acceleration.” (Source:

Soft Starts can last up to 10 years, depending on how they are being used and maintained.

Soft Start vs. Hard Start vs. Easy Start

Soft Start

Soft Start is a mechanical tool that helps reduce the big current draw during the start-up of RV ACs: “…a soft start is used to protect the motor and your appliances from a shorter lifespan. The soft start reduces the inrush of current by up to 70%, reducing the potential damage from occurring and allowing the motor to startup more smoothly and safely than a hard start.

Soft starters are best used when the power source is a small generator.

For example, soft starters can be used in RVs when you need an AC unit working but you don’t have access to mains power. A hard starter will not work with a small generator, so they are useless in an RV powered by a generator.

A soft starter also contains a start capacitor and a start relay like the hard starter. However, the soft starter also uses comprehensive electronics with impressive algorithms that can sense and record numerous things in the startup of your motor.” (Source:

Hard Start explains the Hard Start really well:

“A hard start is where the inrush of current is spiked to reduce the time taken to get a system started up. You can use a hard start when your electrical current needs a boost to get the motor starter.

The inrush of current is heightened which can put your motor at risk of overheating or suffering a shorter lifespan.

Hard starters are most helpful when it comes to large AC units within residential or commercial buildings. You can use hard starters when you have a powerful power source that is able to offer your AC unit motors enough power to manipulate the inrush of current enough.

A hard start kit includes a start capacitor and a start relay. Plug the hard start kit onto the run capacitor with two wires, incredibly easily and quickly. You’ll need no professional to help with this installation. Hard starters begin at a mere $10 online, so they’re worth a try if your AC is not turning on properly.

Many people are surprised at how simple the fix is to install an inexpensive device into the system before starting it up. Your motor will begin as soon as the hard starter is installed, so you can get your system fixed within minutes.” (Source:

Most old RV AC units have a hard starter installed already. If the compressor is at the end of its life, you will need a new one installed or to purchase a new air conditioner altogether. However, if the compressor is struggling to turn the motor on, installing a hard start kit could fix this issue without having to spend a lot on a new AC.

Easy Start

EasyStart™ by MicroAir is designed to connect directly to the compressor motor and reduce the power surge that occurs on start. It does this by controlling the power supplied to the windings of the motor on each AC cycle. EasyStart™ gradually increases this power until the compressor is running. (Source:

What Size Soft Starter Do You Need?

In principle, soft starter size should be larger than that of the motor being driven. The rated capacity of the soft starter is usually chosen according to two nominal values, one is corresponding motor power, another is maximum allowable working current of soft starter.

Keep in mind that if you have 2 AC’s, you should purchase a Soft Start per unit.

When shopping for a Soft Start, consider the price, time on market and customer satisfaction (incl. failure rate-check customer reviews), as well as ease of install.

What Is The Best RV AC Soft Start?

Some of the major leading Soft Start brands out there are SoftStartRV, EasyStart, SmartStart, Sure Start, and MircoAir.

These Soft Start brands are all comparable in pricing and most have comparable features (athough each brand will claim to be the best). The cost ranges anywhere from $219-$610.

These units work with all the major RV AC brands, such as Coleman Mach, Dometic Brisk, Rec Pro RP, Universal, GE and now even Furrion.

Soft Starts can be purchased on their individual Websites, as well as at major camping supply stores (such as Camping World), in “brick-and-mortar” stores, as well as online. Many RV dealerships might also carry them to install in their customer service and repair center. Finally, carries most, if not all of these Soft Start options.

How To Install A Soft Start On An RV AC

After watching several DIY videos on how to install a Soft Start on your unit, it is much less intimidating to install a Soft Start yourself. Of course, there are individuals who struggle wtih heights/climbing up on the RV roof, or who are not comfortable with electrical wiring work.

However, if neither of those two options are an issue for you, you should be able to follow the instructions and succeed in the install. Just make sure you take your time, are following the instructions deliberately step-by-step and test your work before you close up the AC unit.

The step-by-step instructions are listed in the “Soft Start Installation Instruction” section below.

Some of the tools you will need are a ladder, screwdrivers, pliers, wire cutter, wire splicer, wire crimper, Soft Start instructions and the provided parts kit. Some individuals also bring a wasp spray (in case there are any wasp nests etc.) and silicone etc. to reseal any open wiring cavities after they are done.

Since this project shouldn’t take more than 30 minutes, it should be ok to disconnect the entire RV unit from electricity to keep on the safe side.

What Is Included In A Soft Start Kit?

These are the items that come with your Soft Start Install Kit:

  • Soft Start unit
  • Wires (4 or 5 different colors, depending on which unit you purchase)
  • Wire crimp connectors
  • Wire connector endings
  • Screws (to attach the Soft Start unit to AC)
  • Zipties (to group and attach wires together for a clean look)
  • Double-sided tape (if you want to attach the Soft Start that way, rather than using screws)
  • Alcohol wipes (to pre-clean the AC surface for the double-sided tape)

Soft Start RV Installation Instructions

Erik from TechnoRV shares in a video the step-by-step instructions on how to install a Soft Start on a Coleman Mach AC. (Source:

There are 5 wires in this setup, which makes it pretty stratigh-forward. Keep in mind that each RV AC brand is different and should have their own diagrams and instructions that are unit-specific.

Follow these steps below if you have a Coleman AC:

  1. Cut off the power to the AC completely
  2. Print the instructions or have the images ready
  3. Place the end terminals on the wires from the Soft Start for the black, blue and yellow wires. These are included in your Soft Start Kit.
  4. Take the cover off the AC and the side-panel (if applicable) to access the run capacitor
  5. Take the blue, yellow and black wires from the Soft Start and place them into the area of the run capacitor
  6. Remove the white wire from the run capacitor
  7. Connect the white wire you disconnected to the blue wire from the Soft Start. The terminal has a hook that should hook into the white wire connect, making a solid connection betweehn the two wires
  8. Take the black wire from Soft Start and put it where you just removed the white wire from the run capacitor
  9. Take the yellow wire from Soft Start and connect it to the area where the red wire is on the run capacitor
  10. With the brown and red wires remaining, locate the blue or black compressor wire and splice it.
  11. Connect the brown wire of the Soft Start with the black wire going to the compressor and the red wire with the black wire that connects to the capacitor.
  12. Use the Soft Start provided wire connectors to make the wire connections of the spliced wires. Crimp the wires with the provided connectors.
  13. Ziptie the wires to clean things up.
  14. Reconnect the power to the AC and test the unit to see that it’s working properly. A green light should show up on the Soft Start.
  15. Attach the Soft Start upright on the side of the AC to ensure it is going to remain waterproof.
  16. Re-attach the covers to the AC.

Total time spent on this project: approx. 30 min.

Difficulty level: easy

Tools needed: ladder, screwdrivers, pliers, wire cutter, wire splicer, wire crimper, Soft Start instructions and parts kit

DIY Installation

There are several videos on YouTube on how to install a Soft Start, because this is actually a pretty easy RV DIY project.

Above was the example of a DYI install of a Soft Start on a Coleman AC unit. There are many different RV AC units out there. Soft Start has specific install instructions for each AC model, so make sure you get the serial number off the unit and download the instructions from the Soft Start Website:

Some othere DYI videos on two of the more popular RV AV brands are listed below.

All About RVs shares how to install a Soft Start on a Furrion AC model: 

JonesN2Travel shares on how to install a Soft Start on a Dometic AC model: 

Are Soft Start Kits Worth It?

The Internet is full of testimonials and videos on how Soft Start is a game changer when it comes to RVing, especially in warmer climates (hello Arizona, Florida and Texas!), because it allows you to run 2 AC units effortlessly, even on a 30 Amp circuit. With the fact that it reduces the wear and tear on the AC, the Soft Starts truly pays for itself in no time.

Some of the benefits are:

  • Start 2 RV ACs with small generator
  • Run 2 RV ACs on 30 Amp (with 2 Soft Start units)
  • Compressor Overload Prevention
  • 90-day satisfaction guarantee
  • Free tech support
  • Easy install
  • Waterproof and fire resistant case.


Does a soft start void warranty?

Legally, it shouldn’t, because there is no causal effect to void the warranty. Micro-Air also offers FREE Extended Warranty.

Are soft starters bad for motors?

No. In fact, the opposite is true. The soft start reduces the in-rush of current by up to 70%, reducing the potential damage from occurring and allowing the motor to startup more smoothly and safely than a hard start. Soft starters are best used when the power source is a small generator.

Does a soft start kit save energy?

Short answer is no. The use of soft-start equipment can lead to savings, but it won’t reduce the demand charge on your electricity bill. When a motor starts up, it draws a lot of current. This so-called inrush current is often five to six times the motor’s full-load running current.

Does a soft start hurt your AC?

No. Simply put, a soft starter lowers this in-rush of current by 70%, making it much safer for your AC units to run both of them. What’s more, a soft starter will remove the thumping noise that your air conditioners make throughout the day and night, allowing you to enjoy AC as you sleep with no interruptions.

Can an inverter run an RV AC?

The short answer is yes. With the proper equipment and enough batteries, you can run your RV AC unit on batteries. In addition to the lithium batteries, you’ll need an inverter to invert the DC battery power into AC power for most air conditioning units.

Can you run your RV AC while running other appliances?

With a soft start, yes. However, this also depends on your source of power and whether you are on shore-power (20, 30 or 50 Amp).

Can you run your RV AC on a portable generator?

To power the average RV air conditioner, the generator needs to have at least a 2000- 4000-watt capacity. There are a lot of factors involved in what size generator will work best for you, but for the most part, you will be able to use your AC and other appliances even with a 2000 watt generator.

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