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Old 06-22-2010, 10:43 AM   #1
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Capacitors and Contactors


Hi,

Due to my wife's health issues I like to keep spare parts around. My Condenser is a Goodman. I have had to replace the contactor on it two times in three years. Got two basic questions. Probably simple questions, but here they are.

1). Is a 24 volt, 30 amp, two pole contactor pretty much the same no matter the brand? That is, If I order one it will work? Right now there is a Siemans contactor on the unit. I will tell you that it originally had a 24volt, 25amp single pole on it. When that one quit the repair guy used a 30amp two pole. According to the schematic there is no compressor heater on the unit and the two pole works perfectly. What's up with that. I have looked at the schematic and cant see why it would have used a single pole.

anyway, next question..

2). The run capacitor has a label that reads as follows:

40/5uf +/-5%, 350-370VAC

I am guessing that I can buy a: dual run 40+5 mfd, 370VAC capacitor as a replacement should the capacitor quit. Is this correct?

I really appreciate any help. My wife has had organ transplants and doesnt do good if the AC goes out when it's nearly 100 degrees out with 88% humidity. I like to stay on top of the AC unit. My service guy came out ans serviced it about a month ago. But, I like to be able to get her up and running without the stress.

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Last edited by falconbrother; 06-22-2010 at 10:45 AM.
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Old 06-22-2010, 10:54 AM   #2
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Capacitors and Contactors


you are correct. you could get a 40+5 mfd 370 or 440 VAC, either will work fine. i'm like you, i always have at least one extra cap on hand, just in case.

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Old 06-22-2010, 11:13 AM   #3
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Thanks a lot. I'll do that asap. Was I correct about the contactor? Any 24volt, 30amp, two pole will work? Seems logical to me that it would work.
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Old 06-22-2010, 11:16 AM   #4
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i'm not sure about the contactor. i'm sure someone will jump in and answer that one.
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Old 06-22-2010, 02:02 PM   #5
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To get a reasonable operating lifetime out of it, the contactor contacts should be rated for a motor load, as opposed to a resistive load.
Maybe they all are.

The current required to operate the coil for the substitute contactor should be the same or less as that of the original.

Last edited by Yoyizit; 06-22-2010 at 07:00 PM.
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Old 06-22-2010, 03:44 PM   #6
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Probably one of the reasons your contactor has gone out so often. Is your using the wrong contactor.

It should be a single pole for a Goodman.
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Old 06-22-2010, 04:50 PM   #7
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As a minimum, I would upgrade your capacitor to a 440V rating. Capacitors have been causing lots of issues lately. They almost always come from China or Mexico and are crap.

I had one go out on my 3 year old Rheem last summer and it was an Aerovox and was made of plastic and came from Mexico. I dissected it and the connections had come off internally!!

If you want a decent capacitor get an Amrad Turbo200. They're made in the USA and very high quality.
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Old 06-22-2010, 10:29 PM   #8
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Thanks for the info. I ordered a Goodman capacitor. If Im reading it correctly it's the upgrade for the one that is on it now. As to the contactor. Got some further questions. The single pole 25amp that was on it lasted about six months. The 30amp two pole that is on it now has been there for the longest time, about a year. I read the schematic in an effort to go back to a single pole and just didnt see where it laid that out. It looks like one side of the contactor goes to the fan motor and one to the compressor. I cant see which one would take a closed circuit all the time. An HVAC tech told me to look for a compressor heater but, that's not on the schematic. The guy who services my system says that he doesnt think this unit would have one as it's AC only (gas heat) and only runs in the warm months. I took the 25amp single pole off and replaced it with the 30amp dual but, cant remember which side was the closed circuit. Doesnt matter for now. The system is three years old exactly and been running a 30amp two pole contactor for two and a half years.

I have a good friend who is the HVAC guy at work. He says don't worry about it. He says that the 30amp two pole will do just as good or better than the original 25amp, single pole. So far he is right.

Nevertheless, I find this stuff really interesting. I really appreciate all the input. Like I said before, AC is not optional in this house due to medical issues. And it's bloody hot here right now.

Beenthere, can you tell me which side takes the closed circuit? If I go back to the single pole should I move up to a 30amp or go back to the 25amp?

Last edited by falconbrother; 06-22-2010 at 10:32 PM.
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Old 06-23-2010, 06:23 AM   #9
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It doesn't really matter which side.
Generally, when looking at the mounted contactor. The left side is the closed side.

Check your start and run amps.
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Old 06-23-2010, 10:14 AM   #10
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Cool, I saw a 25-30amp single pole contactor. Im gonna go with that.
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Old 06-23-2010, 07:23 PM   #11
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What happens to the contactor when it fails? does it stick open. burn out the coil or contacts? A faulty thermostat or el cheapo will sometimes not close cleanly and will cause the contactor to chatter and fail prematurely.
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Old 06-24-2010, 12:03 PM   #12
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The 24 volt coil shorts out. I suppose that is caused by the cahttering you suggest. I checked and it's at least 24 volts coming in so I cant explain why the contactor would burn up/short out the 24 volt coil. The actual contacts look OK. This hasnt happened in a while. I has a Siemens contactor and replaced it with a Siemens. Seems like a quality product. Better, I think than what was on it from the factory.
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Old 06-24-2010, 12:31 PM   #13
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It isn't the contactor. Its a short or bad connection in your wiring some where.

What brand and model thermostat do you have.
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Old 06-24-2010, 02:14 PM   #14
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It's a Honeywell electronic programmable from Home Depot. It's the second one I have tried. As far as I know there wasn't a bloody thing wrong with the old one which was also electronic.
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Old 06-24-2010, 02:14 PM   #15
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Story of my life..

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