Hard Start vs Soft Start-Help me understand better?

Now that it's warming up again and I fired up the AC in the house it reminded me of something. About a year ago my AC stopped working, fairly new unit. I had a tech come out and he determined the Capacitor was bad. Anyway, it was two guys, they spoke spanish and I speak a bit of spanish, so I said a few things to them in spanish and offered a soda. Anyway, I think the fact that I was nice and spoke their language opened the guys up and they were my best friends.

He ended up doing some further diagnostics and suggested the unit needed a hard start kit, which I take to just be a higher capacity capacitor? He gave me a good price on the kit. He tried to explain to me why it needed it but I didn't quite follow what the issue was. I asked about a soft start and he said that would be better but he didn't have one on the truck and they are a lot more expensive and felt the hard start was fine. He also hooked up gauges and said the system was overcharged when it was installed and corrected that as well. He also cleaned the outdoor unit and gave me some extra cleaner and gave me some vibration pads to put under the unit. The system cools better now than it did before his work but has always seemed loud on start up. He said the overcharge may lead to a shorter "life" on the compressor over the long run.

Why would a fairly new (less than 3 years old at time of service) AC need a "hard start"? Should I replace the hard start with a soft start?

A hard start is an oversized capacitor that gives the compressor a bigger kick in the pants to get it running, but is switched out if the circuit shortly thereafter. It is a band aid solution for failing equipment in my experience. I.put one on my AC two years ago after hearing it humming loudly trying to start a few times. It has worked well, but I took it as a sign my 25yr old unit is getting tired.

duneslider said:

The system cools better now than it did before his work but has always seemed loud on start up.

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I was curious about one of my units that does the same thing. I was told that it is the "scroll" type compressor and it's common to this compressor type. Basically sounds like you clapped two boards together at start up. The new capacitor shouldn't make it cool better, but should make it start (which won't happen if the cap is dead). No idea if a bigger capacitor will change the noise of the compressor start.

The only place I use "soft starts" is in an RV where you have limited power available - reduces that current surge required to start the thing. With a soft start, I can get a 15k BTU unit to run on 2500 watts of generator....

I asked about "preventative" cap replacement also, tech said he sees caps last 3 years and some more than 15. YMMV.

A soft start will significantly reduce the startup current of the compressor.

It also eliminated the remaining light flicker when the unit turned on for my system. A good part of the light flicker was eliminated with a smart contactor.

And yes, a soft start kit is considerably more money than a hard start kit.

dcg9381 said:

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I asked about "preventative" cap replacement also, tech said he sees caps last 3 years and some more than 15. YMMV.

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You can check them with most meters. When they're out of range just replace them.

You should not have needed a hard start kit unless something was wrong. Those are typically only used as a short term bandage for something like a really old compressor that needs more power to get it going. Unless somehow the overcharge damaged yours in a way the hard start compensated for, I don't know why you would need one.

A soft start is a great device to reduce startup amp draw and quiet down a compressor. A hard start does the opposite and in theory kills the compressor faster.

Putting an Easy Start ASY-368-X48-BLUE soft start on my 20 year old, 3 ton, 13 seer AC dropped startup amps from around 70 to around 20. Also my lights no longer dim when the AC kicks on, and it's very noticeably quieter starting up.

Kinda sounds like a successful salesman.

danski0224 said:

A soft start will significantly reduce the startup current of the compressor.

It also eliminated the remaining light flicker when the unit turned on for my system. A good part of the light flicker was eliminated with a smart contactor.

And yes, a soft start kit is considerably more money than a hard start kit.

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From your past posts, I have gathered you work rather extensively with HVAC systems.

What brand of soft start did you install on your system?

I have been thinking of installing one of these on our 3-ton 14 SEER Goodman heat pump outdoor unit.

Snapped-off said:

Kinda sounds like a successful salesman.

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Probably, but it wasn't expensive, can't remember now but I think it was like 40-50 bucks and the service call was all warranty, so I didn't really get charged for the two guys there other than the 40-50 bucks.

WildBill said:

You should not have needed a hard start kit unless something was wrong. Those are typically only used as a short term bandage for something like a really old compressor that needs more power to get it going. Unless somehow the overcharge damaged yours in a way the hard start compensated for, I don't know why you would need one.

A soft start is a great device to reduce startup amp draw and quiet down a compressor. A hard start does the opposite and in theory kills the compressor faster.

Putting an Easy Start ASY-368-X48-BLUE soft start on my 20 year old, 3 ton, 13 seer AC dropped startup amps from around 70 to around 20. Also my lights no longer dim when the AC kicks on, and it's very noticeably quieter starting up.

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I looked at that and it seems I have seen those on the RV forums for AC units. They seem to have a good reputation. They aren't terribly expensive, maybe I should look into getting one.

larry4406 said:

From your past posts, I have gathered you work rather extensively with HVAC systems.

What brand of soft start did you install on your system?

I have been thinking of installing one of these on our 3-ton 14 SEER Goodman heat pump outdoor unit.

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Micro-Air makes a nice one.

This is what Gould uses for soft start with multiple changeable parameters...............

There are two types of hard starts . One uses a potential relay and start capacitor the other is a two wire solid statethat just goes across the run capacitor which both work well.
://www.amazon.com/SPP6-Capacitor-Increase-Starting-Torque/dp/B0002YTLFE/ref=mp_s_a_1_9?dib=eyJ2IjoiMSJ9.iWAP2KkQUghE9LZbJqR1P9b3-yqjKbB7KI4oYA6sn5OuvrD2z0GYEcbFlG5ijEVo0tUq66zAOVbcvS7Bd4z9OK4rKSnBH6QfpNwWW07QMqPOZZeVsj-Acha4m2V2KmJjcqAUS7NqsAsUTYHeSlu-jGYKo5Hrd1Rg1vF0SShrkP2whSqv_9D3t8-MB93df-0EEQv6JdfZy0DuN_X6JQV0HQ.PEfibPCsDMWzwOfJCDR9EpZtAhg53P13vFHsGvKEScU&dib_tag=se&keywords=hard+start+kit+for+air+conditioner&qid=1779378434&sr=8-9

I had a NuStart installed recently, after several cycles it dropped from 63A to 17A on a 5 ton Rheem and was noticibly quieter and no more light flicker. Cheap? No, but if I get extra years out of the compressor it will be worth it it, imo. Time will tell.