5.0 out of 5 stars Eliminates AC compressor start-up "thump" and restores your sanity!

L. · August 11, 2024

(function() { P.when('cr-A', 'ready').execute(function(A) { if(typeof A.toggleExpanderAriaLabel === 'function') { A.toggleExpanderAriaLabel('review_text_read_more', 'Read more of this review', 'Read less of this review'); } }); })(); .review-text-read-more-expander:focus-visible { outline: 2px solid #2162a1; outline-offset: 2px; border-radius: 5px; } This soft start device is a game changer. We have a Goodman 5-ton condenser that starts each time with a loud, but normal, "thump" as the compressor gets hit with 130A start-up current. Residential condensers work this way by design since it requires the least amount of parts (simple contactor and run capacitor) and is therefore cheaper to manufacture. All of this is fine if your AC unit is located far enough away from your living space that the start up noise is not bothersome.Unfortunately, like most homes, our AC unit is installed on the side of our 3,000 sq. ft. house and you can hear the condenser start from most rooms. A good amount of the start up noise is amplified by the refrigerant lines that enter the house, go up the wall, and then over the attic space to the furnace/AC unit in the middle of the house. I have tried condenser mounting pads on the slab and an additional support bracket for the large refrigerant line but nothing has reduced the reverberating "thump" noise at start up.My research into this issue showed that people generally try to solve one of two problems with their AC units: "not enough" start problems and "too much" start problems. The "not enough" start camp winds up installing hard start capacitors to give the compressor an extra jolt so that it starts up reliably. This can be useful for older compressors or for units where the owner hasn't diagnosed other faults such as a worn out start/run capacitor. The other camp searches for ways to reduce the "too much" start problem that causes high current draw (a problem for generator/solar power sources), noise, and wear-and-tear on the compressor that I mentioned earlier.Which brings us to the electronic soft starter. This device is specifically designed to control the compressor in-rush current at start up and thereby reduce high power inrush, unnecessary noise, and wear on the compressor motor. It gradually accelerates the motor up to speed instead of hitting it with full current all at once. It's like accelerating in your car by gradually pressing the accelerator as opposed to slamming down the pedal and going full throttle from every stop. Both get you where you want to go but only one method does so without unnecessary power consumption, noise, and wear-and-tear.Installation of the AIRGO device is very straightforward for the technically-inclined and for those familiar with AC condenser components. The kit includes all the additional wires you need with pre-crimped terminations that makes installation in a standard AC unit easy. It turns out that the AIRGO unit is identical to the Eltwin soft starter (also sold here) but has different branding and, frankly, a much easier to understand connection diagram. I did create my own connection diagram (see photos) so that I could fully understand the connections as they related to my system (I also replaced the contactor and run capacitor at the same time). NOTE REGARDING WIRING: It doesn't matter if you have a single pole or double pole contactor. You can use either type per AIRGO with no wiring differences whatsoever. I did find (on Eltwin's soft starter website, btw) a schematic showing the soft starter "ACTIVE (T)" wire connected to the switching pole of the single pole contactor and the "COMMON" wire connected to the pass-through pole. Again, it makes no difference which pole is used but I wired it per the Eltwin schematic anyway. This is shown in the photo attached.Once connected, everything worked perfectly and exceeded my modest expectations. The AIRGO soft starter has COMPLETELY ELIMINATED THE START-UP "THUMP" NOISE from the compressor. It's totally gone. When standing next to the condenser, the ONLY start up sounds are the simple click of the contactor and then a slow whooshing sound as the compressor and fan come up to speed in less than 2 seconds. Inside the house, the only way we know that the condenser has turned on is when the interior HVAC fan powers up. No more jolt, no more “thump” —completely gone.In summary, the AIRGO soft starter delivers everything it promises and is worth every penny to restore peace and quiet to your AC condenser start-up. The AIRGO (aka Eltwin) soft starter device appears to have been around for at least 10 years which speaks well of its ongoing value and overall reliability. I expect the device has been refined to the point that it will deliver years of service when properly sized for your system and installed correctly. I only wish I had discovered this device years ago! Oh well, if you install one, you'll quickly forget the few extra dollars you spent on this quality device. For me, it paid for itself on the first start up.Thank you, AIRGO!

5.0 out of 5 stars Works as advertised but cable connectors could be improved to ease installation

R.S. · July 10, 2025

I was a little hesitant to mess with my HVAC, but I wanted to be able to use lower power generator for my home, so I decided to do it myself. I'm quite handy with electrical systems. The only issue I encountered, was that my HVAC had loop connector on the red contactor wires, instead of ferrule one that is the default on the supplied cables. I had to run to HD to get the right connector and to replace it on the supplied red cable. I believe most contactors use loop connectors, so it would be better for the manufacturer to provide it on the red wire, instead of ferrule. Another thing I had to do was to change the connector on the yellow wire to loop as well since I did not want to cut the compressor wire to change it to ferrule type that could plug into the Airgo in case I need to remove it in the future. It was easy to join two loop connectors with a screw. After doing these cable retrofits, everything went smoothly. The device was small enough to fit inside the electrical enclosure in the compressor unit. I verified significant startup current reduction from 84 to 34 amps. It might improve after a few learning cycles according to other folks. This will allow me to use smaller gas or solar generators with 8500W surge power or above. An added bonus is that the lights don't flicker and there is no "knock" sound anymore when the compressor starts up. This should also prolong the life of the compressor. Overall, I'm happy with this product. I included before and after photos.

5.0 out of 5 stars Great soft start!!

D.c. · July 7, 2025

This soft start is well worth the money. My lennox 2.5 ton compressor used to thump hard upon start up. Immediately after installing the soft start, the thump stopped! The only thing you can hear now is the sound of the contactor getting sucked in and the fan turning on, thats it! Amazing product. Installation is very simple. Just read the wiring diagram on the condenser unit and follow the instructions that come with the unit. When the instructions talk about hooking up the black wire from the airgo to the load side of the contactor and the red wire from the airgo active to the loadside contactor, that is the side opposite on the contactor of where your power (240v etc) is connected to the contactor coming from the disconnect or breaker. Very simple. Also the amperage dropped from 67 amps to 32.3 amps upon startup. Works great.

5.0 out of 5 stars Great product and kit for a noisy compressor start

J. · June 19, 2025

This soft start kit works great! It immediately solved the loud thump on compressor startup and inrush current is much more reasonable.The included wire jumpers are quality stranded copper, appropriate heavy gauge for each circuit, and arrives with complete accessories for solid connections on each side. Those added conveniences made this kit truly plug and play for me. As others mentioned the included instructions are easy to follow. Stay cool!