AC won't start on SureStart (used to work)

[bbatchelder]

Hello!

I have a 24kW Generac, and my house has 2 AC units (I'll attach their panel info - both are Rheem and one is a 4 ton and the other a 5 ton). They would not start under generator power, so I bought 2 SuerStarts back in July 2021, and had them installed by my AC tech. We tested them and they both worked just fine after the SureStart units were installed.

Here are the details on the SureStarts: Hyper Engineering Sure Start A/C Soft Starter SS1B16-32SN For 16-32 RLA A/C Units × 2

We just had a power outage yesterday, and while the smaller 4 ton unit seemed to work fine, the 5 ton unit was not cooling (though it was blowing air). Every 3 minutes the lights would dim and the generator would bog down for 1-2 seconds.

I turned off the 5 ton unit, and the symptom of the lights dimming every 3 minutes went away (as did the generator bogging down).

I turned off the 4 ton unit and tried running the 5 ton unit again, and had the same issue with it not cooling and every 3 minutes the lights would dim/generator bogged down. I also tried with basically all lights turned off - so as small a load as possible on the generator.

So something is off with the 5 ton unit. I am going to put in a service call to my AC tech, but I wanted to come here as well and see if anyone has experienced this and/or has any idea what the issue may be?

I am *hoping* that its maybe a start/run capacitor going bad in the 5 ton? Does that seem reasonable?

My AC tech seemed to be knowledgable about the SureStart units, but if you have any suggestions for things I should ask them to check out, I'd appreciate it.

[Chris]

I would say I agree that the run cap in the unit may be failing. The Sure Start does still rely on that to start the compressor. I would leave that unit off until you can have someone check it out though. That dimming and surging from the gen is the compressor locked up and then opening either the overload feature in the Sure Start, or the thermal overload in the compressor. Enough tries and it can do some damage

[bbatchelder]

Hey Chris!

So my AC tech checked the capacitors and they were within spec, but when he tested the Sure Start he determined it has started to fail - he said it was only pushing 155mfd when it should be more like 200-240mfd.

What is the warranty procedure?

Thanks!

[Chris]

Will you send me an email at the same info email that sent you the order confirmation for the Sure Start order? Please include pictures of the Sure Start installed and a picture of the SS's serial number tag.

This is the first genuine failure I've heard of with these, so I want to make sure and gather as much information as possible about it!

I've never heard of anyone measuring capacitance out of one of these, so I'd be curious to know where he came up with those numbers and what he was measuring?

Did he remove the Sure Start?

Thanks!

[bbatchelder]

Email sent with the details you asked for.