2-Wire and 3-Wire Hard Start Kit

2-Wire vs 3-Wire Hard Start Kit – Comparison of 2023

In order to ensure the longevity of your AC unit at home, you may need to take good care of its compressor. However, it is inevitable to maintain its reliability in the long run due to normal wear and tear. The good thing is that you don’t need to replace the compressor immediately, you just need some sort of a twist!

This is when the functionality of a hard start kit comes in. In this guide, let us understand the difference between the 2 wire vs 3 wire hard start kit.

But first, it is worth noting that both of these can aid a compressor to start in case of an undesirable condition – high head pressures or low voltage – occurs.

With this, you can improve the effectiveness and speed of your unit. Of course, we understand that there are numerous kits available on the market.

And it may be challenging to find the right one, so we’ve narrowed down the best items for you!

2-Wire vs 3-Wire Hard Start Kit Comparison 2023

2-Wire Hard Start Kit

First off, a 2-wire hard start kit is usually a more convenient way of providing extra torque to the compressor and does not need a third wire to connect to a common wire. Here is the list of some of the products that you can buy in the market today!

1. Packard Universal Replacement 2-Wire TorQ Start EM Hard Start Kit

This product had to come first on our list and that’s because it has received a lot of positive feedbacks from its customers. Let’s get to know why by getting familiar with some of its great features.

The TorQ Start is a two-wire pre-assembled starting component that can be installed on your system with ease. It comes with a start capacitor and a mechanical potential relay that are made of high-quality materials, thereby ensuring durability.

It can be utilized for single phase 265V, 230V, and 208V with 1.5 to 3 tons applications. So, its applications can be mostly found on heating, ventilation, air-conditioning (HVAC), and refrigeration condensers.

Much more, it can be used with prominent brands like Carrier, AAON, Payne, Armstrong, Bryant, Bard, York, Philco, and many more. There is more that you can do with it because it can also replace kickstart KS-8, TO-5, SPP6, CSR-U1, SK3W3, and many other hard start devices.


  • Effortless and quick installation
  • Can be utilized on 208V, 230V, and 265V
  • High quality, unique design
  • Compatible with prominent brands
  • Replacement to many types of hard start devices
  • For 1.5 to 3 tons


  • Hard to look for available replacement parts

2. Packard 2-Wire TorQ Start EM Hard Start Kit

Another kit from Packard made it to the list of our recommended kits. This TorQ Hard Start Kit is basically considered as a universal replacement for compressors. It is made with a lot of great features too.

This is a combination of a mechanical potential relay and a start capacitor that allows it to do the job efficiently. It can be used for equipment with as high as 265V and as low as 208V and with a tonnage of 3.5 to 5.

Installation is just easy since it is already pre-assembled in the factory. All you have to do is to set it up with your equipment, and then it is as good as new. Much more, it can be used on different brands’ products that have a hard start-up – making it a very versatile product!


  • Universal replacement
  • Fast and easy installation
  • High-quality
  • Can be utilized on various brands and equipment
  • Used in Condensers for HVAC and Refrigeration


  • Replacements are difficult to find

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3. KS1 KickStart Hard Start Kit Rector Seal 96506

If you want to extend the life of your compressors at home, this product is a good choice for you. Well, this kit has a proven record of performance and reliability. Not just that, there’s more! Read on to discover all of the amazing features that make it stand out from the rest.

First, it is made with a unique design that is patented by the manufacturer. This reason alone is what mostly keeps Kickstart apart from its competitors. And it has undergone continuous research and development, which earned them a product approval from the leading manufacturers of compressors and equipment.

In fact, Kickstart is the first one to get that approval for any two-wire starters in the HVACR industry. So, look no further beyond this product when you are purchasing a hard start kit for your system.

This is a 2-wire product that comes with a start capacitor and a mechanical potential relay. Much more, it can be utilized on 3.5 to 5-ton maximum torque hard start equipment. It is also recommended to be used on a single phase 208V, 230V, and 265V air conditioner, refrigeration, and heat pump compressors.

But then, this requires you to let a professional or any licensed contractor install this product into your system for safety purposes.


  • Comes with an original patented design
  • Reliable
  • Great performance
  • Recommended by manufacturers of HVAC Equipment


  • Might be pricey

4. Wadoy AC Hard Start Capacitor for 5-2-1 CSR-U1

For sure, you’re looking for a high quality and efficient product that can be a solution to your problem. Good thing that you have come this far as this might be the best choice for you!

This hard start kit is usually utilized on air-conditioner units with 1-2-3 tons. Well, it is known to have incredible performance and functionality. This product has an installed 5-2-1 compressor saver. With this, you can significantly reduce the amount of time when your compressor is on high ampere start-up.

Much more, using the smart switch and a dominant multi-layered starting capacitor, you can provide your compressor the boost that it requires to start up quickly and efficiently. Through this, you’ll able to utilize lesser power – making you save a lot of money.

Moreover, installation is never a problem with this product since it has only three wires to be connected: a black wire to the common side of the compressor, a striped wire to the start winding of the compressor, and a red wire to the run winding of the compressor.

And even though your compressor doesn’t experience any trouble at all, you can still install this to make your system last longer by letting it spend less time on start-up.


  • Higher stability
  • Comes with safety features
  • Ensures optimum performance
  • Easy to install


  • Not reliable

5. CPS 5-2-1 CSRU3 Compressor Saver

If ever you’re looking for a product that is particularly made by technicians for technicians, this one from CPS is a good idea! It ensures that you will be getting immediate results. Well, no doubt why it made it to the top as it delivers innovative solutions since 1989.

Anyway, this product is definitely capable of reducing the in-rush current of up to 50 percent. In-rush current usually occurs during start-up where there is a surge in current when the power is first applied to your unit. If this happens, it can consume about 45,000 watts. And the best solution for this is to use this compressor saver.

The device can significantly limit the time the compressor spends in a start-up that usually draws high amperage. This is done by using a multi-layered starting capacitor and a smart switch. When it starts quickly, it utilizes less power. And less power means fewer energy costs too!

Additionally, the existence of voltage surges and spikes can cause a lot of damage to any HVAC equipment. Not only does it reduce its efficiency, but it can also shorten the life of your compressor. Since this product is equipped with a patented thermal protection MOV technology, this is certainly ideal for your devices at home!


  • Affordable
  • Can reduce in-rush currents up to 50 percent
  • Has maximum protection for voltage surges
  • Helps you save energy bills
  • Easy to be installed at air-conditioner disconnect, junction box or panel


  • Cannot be reliable at times

3-Wire Hard Start Kit

When there is a need for a third wire connection to the common wire, a 3-wire hard start kit should be utilized. Below are some of the best kits that you can find in the market today!

6. Supco RCO810 3-in-1 START Hard Start Kit

If you want something that can do the job in protecting your system from any damage, this product is surely for you!

When you have an unbalanced system that experiences hard start, boost it with this 3-in-1 hard start kit. This is a universal kit that can aid you in getting the task done in no time.

It is equipped with a relay capacitor overload device that you can utilize for your refrigerator. You can say that it is versatile since it is compatible with a lot of different refrigerator models in the market today.

Much more, with this, you are allowed to operate your system or refrigerator even when the power is low. You also have the option to set it up and run it with or without a capacitor. Anyway, the capacitor is used if you want an added operational versatility.

The kit also comes with an instruction that can guide you for easy installation in your system. But then, you need to make sure that you have checked the compatibility of this product with your previous one and the model of the appliance before you make the purchase.


  • Not too expensive
  • Ensures versatility
  • Equipped with a set of cover for safety purposes
  • Universal use
  • Comes with instructions that are easy to follow


  • Not suitable for all HVAC equipment

7. Supco Hard Start 3W1

Another product from Supco has made it into our list. This kit comes with an OEM option making it ideal for pros. And it is especially crucial when the system experiences hard start-ups. Without a doubt, this is a good choice since it complies with NATE and UL.

With the combination of a mechanical potential relay and a start capacitor, this product will not fail to provide you with optimum functionality. This can be utilized in the recommended range from 1HP to 3HP with an operating voltage of 208V to 240V, making it an ideal 3-wire solution!

It comes with amazing features that can aid you in your troubles, such as voltage sensing and instant restart. Also, you will not find the installation process hard since it is equipped with an easy and quick snap bracket so you can use it instantly!

For sure, this kit can be used in your single-phase refrigeration unit or air conditioner as well as to any compressors experiencing hard startups in low voltage situations.


  • Voltage sensing
  • Instant restart
  • Equipped with an easy snap bracket
  • Comes with a reasonable price
  • Excellent booster


  • Not suited for higher voltages

8. Prime&Swift CSRU3-3 Wire Hard Start Kit Compressor Saver

A lot of different systems have struggled, especially when it comes to start-ups. It is like the hardest part of the process.

Usually, surges and spikes can happen during this phase, where your equipment can consume 5 or 10 times more power than it needs for running. So if you are tired of this, this kit is the solution to this problem!

It utilizes a start capacitor along with a potential relay to give you a great service. As recommended by the manufacturer, it can be used in a reciprocating compressor of 4 to 5 tons with a voltage range of 208V to 240V only.

You can surely extend the lifespan of your compressor at home without spending too much. It can also aid you in protecting all the internal components to prevent total damage to your unit.

Furthermore, you will be able to start your air conditioner or refrigeration unit with about 30 percent to 50 percent lesser time. With this, you can definitely save power and money at the same time!

This package also comes with mounting screws and zip ties that can help you in installing the product to your unit.


  • Much lesser start-up time
  • Aids in saving power and costs
  • Competitive price
  • Installation is easy
  • Compact design


  • Not compatible with all types of equipment

9. Prime&Swift CSRU2-3 Wire Hard Start kit Compressor Saver

If you want a product that can save you from replacing your old compressor and spending too much money, this kit can help you do the job. And yes, another kit from Prime&Swift has made it to our list.

Using this kit will surely help you save power as well as costs from the payments of your electric bills. You will be able to limit the start-up time of your equipment less than 50 percent than usual.

It does its job by using a potential relay and a start capacitor reciprocating from 208V to 240V with a tonnage of 3.5 to 4.5.

You can surely extend the lifetime of your compressor and protect all the internal components to make sure that your system functions as efficiently as possible.


  • Can be installed with ease
  • Helps to save power and money
  • Easy to use
  • Compact design


  • May not be compatible with other equipment

10. Supco Hard Start, 3-Wire

Last but not least, this product from Supco completed the list. When using this device, no start-ups are too hard as it can provide great units which can help you get your task done with ease.

This hard start kit can be used to equipment with a control voltage ranging from 208V to 240V with an HP rating of 4 HP to 5 HP. It is equipped with a start capacitor and a potential relay to do such a job.

Furthermore, it is perfect for a single-phase air conditioner and refrigeration unit as well as for compressors with a hard start-up, especially when a low voltage situation occurs.


  • Comes with an easy snap bracket for effortless installation
  • Features voltage sensing and instant restart
  • Affordable price
  • Ideal for single-phase system


  • Requires a Mechanical Relay

Wire and 3 Wire Hard Start Kit – What’s the Difference?

A hard start kit can bring many great benefits. First, it can increase your compressor’s lifespan. Second, it will help you with issues regarding low voltage and inadequate cabling. Lastly, it can allow you to avoid spending on replacing a compressor.

The only difference between the two is the existence of a third wire when it is necessary to connect to the common wire in a 3-wire kit. This usually happens when a potential relay opens at a specified voltage, and a start capacitor is removed from the circuit.

A 2-wire hard start kit is considered to be more convenient in providing an increased torque to your compressor. It can add as much torque as a 3-wire can do but with much simpler installation and at a lower cost.

You’ll need a hard start kit if the following factors are present in your AC:

  • AC has tripped your circuit breakers;
  • AC lights are flickering;
  • AC is only operating in short bursts within a few minutes (short-cycling);
  • AC is making clicking and humming noises.


Having a hard start-up kit will definitely offer you a lot of benefits, as mentioned above. You will surely find various products of this kind, but deciding what to buy will be hard. If you are looking for a guide, this 2 wire vs 3 wire hard start kit review should be of help!

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