Hard Start Kit Sizing Help


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Old 06-07-21, 01:17 PM
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Hard Start Kit Sizing Help

My compressor does not start despite the contactor working OK from the T-stat, the fan is running, and I just put a new capacitor in. So I'm willing to put a hard start kit in, but how do I know which one to buy?

I see many 2-wire kits on amazon for $13 and would get that in a heartbeat. But I fear it may not be the right size since I have never installed one before.

My system is a 1.5 ton Nordyne FS3BA-018KA.
The documentation lists Start Relay Kit 912933 ...but it's $100+ when I search for it!!!
I cannot find the specs on the 912933 kit anywhere, when it's listed for sale, there are no specs for me to find a comparable one.

Thanks in advance! It's 90+ degrees and no A/C!





 
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Old 06-07-21, 10:07 PM
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If the capacitor you just put in came out of the box marked "may be good" I would check it's true capacitance first. Next I would look for burns, breaks, or corrosion on the high voltage wires and terminals from contactor/capacitor/compressor, starting at the compressor working back. -I've used replacement wire and terminals much much more than hard start kits-. After that, if you have a meter check for a compressor short and ohm it out at the three terminals. I'm sure you can find a YouTube video that would show you the procedure and the safety precautions to take. Remember to take reference photos before removing any wires. If everything looks good so far, and you still want an Amazon hard start, try one rated in the range of 1 1/2 hp for your 1 1/2 ton system. There's always the option of calling for service if you feel your getting in too deep.
 
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Old 06-08-21, 06:13 AM
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Thank you for your reply fastback! I did call a technician, but they said it'll be several days till they get there.

I took the new capacitor out of the box and put the old one in the box and labeled it "May be good" ...the installed capacitor is NEW.

I did check the wires at the terminals, but it hit me last night that I need to check them at the compressor, so I'm doing that now. I also will check the compressor for a short and report back in a few hours ...thanks!

 
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Old 06-08-21, 09:54 AM
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If the fan is running but the compressor is not..... the compressor may be out on thermal overload.
That will occur within about 10 seconds of power up if there is a capacitor problem.
There would have been a loud hum at this time.
It could take several hours for the compressor to cool off.

Be sure to wear safety glasses while working around the compressor and its connected wiring.
You will kill power to the condenser before checking the compressor.


 
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Old 06-08-21, 10:23 AM
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PJmax, yes, the fan is on, but not the compressor.

OK, I just went to check the wiring and resistance. But the 1st thing I did was push the contactor in ...and the compressor came on! So the compressor probably overheated and shut down yesterday.

Yesterday when I put my hand on the smaller copper line, I swore it was slightly cooler than ambient temp. That would make sense now that I know the compressor probably shut off from overheating.

So, I pulled off the outer shell off the condenser thinking that's one thing that could cause overheating and it was pretty dirty and clogged in some spots. I brushed off the entire condenser and vacuumed it from the outside too. The tenant will be home in 4 hours and will let me know if it starts cooling.

I haven't searched yet, but I assume a partially clogged/dirty condenser can cause the compressor to overheat?

One last thing: yesterday I did verify that there was plenty of air flow coming out of the vents, so I'm assuming the evaporator is not clogged and the filter looked good too.




 
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Old 06-08-21, 06:23 PM
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After cleaning the condenser, The tenant is reporting no cooling.

I'll go over tomorrow morning and make sure the compressor is running, then report back here. I"ll also look at the evaporator coil and make sure there's good air flow through the system and take temp readings if there's any cooling. I'm not sure what's left, but I'll post here tomorrow. Thank you everyone!
 
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Old 06-08-21, 06:50 PM
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Yes...that condenser is pretty dirty. Careful vacuuming is one way of cleaning it.

Spray coil cleaner also works well.
Spray the coil. Let it sit the recommended time and then wash from the inside out.
 
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Old 06-09-21, 11:51 AM
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UPDATE:
I checked air flow again inside the house and it was good. The compressor started up OK too. So the only thing left is low refrigerant.

The technician finally came while I was there (after a 3-day wait) and he did find low refrigerant. He filled it with 2 pounds of R22 plus a stop leak product, and we're working OK now. It's just a matter of whether the leak is fixed or continues and if it does continue, what rate is it leaking.

Thanks to everyone who helped! I learned a lot!! especially that hard start kits really are rarely used. I do not need one after all.

-Tony
 
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Old 06-09-21, 05:36 PM
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Tony17..: I learned a lot!! especially that hard start kits really are rarely used. I do not need one after all.
Actually hardstarts are a big help in starting AC powered compressor motors, when otherwise would not. They activate when line voltage drops as compressor struggles to start, quicly boosting voltage.

Most commercial systems use them.

They can save a lot of costly service calls, so many professonals do not use them to increase income. But companies with service contract use them to reduce calls.

Hardstarts have capacitors that also go bad so keep $15 spare.
 

Last edited by doughess; 06-09-21 at 07:21 PM.
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Old 06-10-21, 07:02 PM
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Tony17..: So I'm willing to put a hard start kit in, but how do I know which one to buy?
Supco Model SPP6 for 1 HP to 10 HP 277 volts:: https://www.supco.com/web/supco_live/products/SPP6.html

Youtube has items on installing them: https://www.youtube.com/results?sear...pco+Model+SPP6
 
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Old 06-11-21, 07:56 AM
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doughess: Thank you very much for recommending a hard start kit for my application. But I need to know how that is determined, not just a one-time prescription. I want to know how to size them for ANY application.

For example, the specs on my system is:
Compressor Amps RLA = 7.9 Amps
Minimum Circuit Ampicity = 10.6 Amps
Capacitor = 25uf, 5uf and 370 Volts
1.5 ton Compressor/condenser
No HP is labeled ANYWHERE, so I I would not know how much HP mine is.

So, do I size it on the existing capacitor's size? the tonnage? the Horsepower (which isn't found anywhere, so I'd be lost if it's HP), the RLA's? Or a combination of these?

Thank you ...I hope to finally learn how this is done.
 
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Old 06-11-21, 09:28 AM
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Tony17:So, do I size it on the existing capacitor's size? the tonnage? the Horsepower (which isn't found anywhere, so I'd be lost if it's HP), the RLA's? Or a combination of these
The hard-start-kit is not a motor run or start capacitor, size of either vary greatly with horsepower.

When compressor motor first starts, hard-start capacitor is not connected or active. Only if voltage drops does it switch on. Look on its as lightening rod. No lightening no current flow.

While your label does not state HP, at 230 volts and 7.9 amps = 1817 watts divided by 736 Watts per HP = 2.468 HP

Supco Model SPP6 is for 1 HP to 10 HP 277 volts motors.
These make connections simple:
https://www.te.com/usa-en/product-61...AaAj_EEALw_wcB
 

Last edited by doughess; 06-11-21 at 11:53 AM.
 

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