AC and capacitor - short circuit?

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  #1  
Old 07-10-18, 10:28 AM
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AC and capacitor - short circuit?

Hello,

I am a typical lurker/reader but I am now writing because I have a question I hope someone can give me advice on.

I was planning to fix my AC, but I have a fairly old AC home system so I decided to call a company this time. The outside unit was not working properly but it was not the fan so I figured it could be the capacitor or compressor - so, anyway I had the AC company coming and look at it. Long story short, the guy comes in, changes the capacitor, but as soon as he relatch the service disconnect outside the house, the unit goes for like 5 seconds, and then I have sparks in my electrical panel, and the breaker is gone. Now I connected to a different circuit breaker and it seems it's ok.

My only question is: could a wrong capacitor do something like that? My capacitor had three push-up terminals on top, what the guy put in (and then removed) was a 5 one. I am happy to pay them for the diagnose, but they have been oddly defensive and I would like to get an understanding of what happened before I do.

Sorry if my terms are not accurate- I do a lot of DIY stuff, just not so much in electrical.

Thanks,

Gabe
 
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  #2  
Old 07-10-18, 11:11 AM
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Using AC model data do a search for correct capacitor and install it. Then buy a "hard start kit" and install it. Kits typically come with wires spade terminals that slip on AC capacitor to function as backup.

https://www.google.com/search?q=hard...hrome&ie=UTF-8

Note in link there are YouTube videos showing how to install them.

Older AC's often have starting problems. Kits are like backups and insurance policies. Even if there is not an issue they are good to have. I keep a spare for mine.
 

Last edited by doughess; 07-10-18 at 11:29 AM.
  #3  
Old 07-10-18, 03:34 PM
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Welcome to the forums.

A correctly wired A/C will not cause the breaker to spark or go bad. It sounds like the wires may have been loose on the old breaker. If the A/C condenser was drawing too much power..... the breaker should have just tripped.

A five terminal cap is still a three terminal unit. Some of the poles have double terminals for easier connecting.
 
  #4  
Old 07-10-18, 05:02 PM
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Yes, repair guy may have installed wrong or defective capacitor which popped breaker. Panel breakers do go bad and sounds like yours did. AC motors draw 3 to 4 times running amps on start up so popped breakers are not uncommon.

These old units are often marginal at start up so even with the correct size cap it may hangup.

As I posted earlier put in the correct cap and a hard start kit. The kit is another capacitor with electronic switch that connects it when voltage on regular cap drops below set point.

It is good practice to install kits on systems that are not having start problem. Electrolytic caps age and fail. The kits just kick in when they do.

ggg80: I am happy to pay them for the diagnose, but they have been oddly defensive
Many AC service people have poor understanding of electrical/electronic issues. They are often just parts swappers who do not understand and cannot explain what is going on.
 

Last edited by doughess; 07-10-18 at 07:27 PM.
  #5  
Old 07-11-18, 08:22 PM
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Thank you so much for your feedback! I will call tomorrow asking what capacitor they installed, and then confront it with my own.
 
  #6  
Old 07-12-18, 06:05 AM
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I would demand a refund from service company for last service call. They caused ggg80 added expense to replace panel breaker and may have damaged compressor.

The correct capacitor is specified by AC manufacturer, not service company

These days whenever there is a problem with compressor starting installing a hard start kit is one of the first things to do. For $15 is is a no brainer. Hard start kits make things go better.

The fact that they did not install a hard start shows incompetency. Even if they have a contract it can reduce expensive service calls.
 
  #7  
Old 07-12-18, 10:28 AM
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The incorrect capacitor may have caused compressor issues but I severely doubt it caused the damage at the panel.
 
  #8  
Old 07-13-18, 10:42 AM
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The incorrect capacitor did not directly damage the breaker. Incorrect capacitors can result in compressor motor drawing excessive current exceeding breaker stated capacity without poping.

Breaker manufacturers current draw charts show they do not pop immediately with small overload.

As the original cap deteriorated it caused AC motor draw while starting to increase without popping breaker. Ultimately when the motor failed to run cap was replaced,

Breakers with marked capacities that frequently were exceeded are more likely to fail. ggg80's wrong cap may be the straw that broke the camel's back of a breaker repeatedly stressed.

In this case of wrong cap and breaker failure seems a stretch of coincidence. I am inclined to connect the dots.
 
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