Author Topic: capacitor replacement for Ruud outside unit  (Read 6568 times)

Offline ddw4170

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capacitor replacement for Ruud outside unit
« on: May 24, 2009, 12:22:27 PM »
I have a blown(actually blew the top off) cap on a Ruud unit, of course this happened on Saturday night before Memorial day weekend. My question is, the original was a 40 + 3 microfarad 440 volt, the only replacement that I could get today was a 35 + 5 micro 370 volt. If I have done the math correctly, this would be multiplied by 1.189, which would make it the equivalant of a 41.6 + 5.9 at 440, so will this damage anything? I plan to get the correct one Tuesday, but don't want to damage the fan motor, it's just so hot, I really need to run the unit. Any help will be appreciated.

Thanks,
DDW

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Offline jumptrout51

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Re: capacitor replacement for Ruud outside unit
« Reply #1 on: May 24, 2009, 12:24:11 PM »
You can replace a 370 with a 440. You CAN NOT replace a 440 with a 370.
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Offline ddw4170

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Re: capacitor replacement for Ruud outside unit
« Reply #2 on: May 24, 2009, 12:27:23 PM »
I am wondering about the microfarad rating, a friend said that this may make the fan run faster and possibly damage the fan motor? I have a little exoerience with appliances(mainly refrigerators and the like) but I am not real familiar with caps.

DDW

Offline ddw4170

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Re: capacitor replacement for Ruud outside unit
« Reply #3 on: May 24, 2009, 12:34:15 PM »
So would this damage anything to run like this for a couple of days? I stuck it in and it is working OK right now, but I definitely don't want compressor problems later.

Thanks,
DDW

Offline jumptrout51

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Re: capacitor replacement for Ruud outside unit
« Reply #4 on: May 24, 2009, 12:35:39 PM »
You can get by on a +- of 10% in a pinch. The 370/440 issue will damage your unit.
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Offline jumptrout51

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Re: capacitor replacement for Ruud outside unit
« Reply #5 on: May 24, 2009, 12:43:58 PM »
What is the horsepower and rpm on your fan motor?
Probably a 1/5 or 1/6 at 825.
« Last Edit: May 24, 2009, 12:46:24 PM by jumptrout51 »
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Offline JWWebster

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Re: capacitor replacement for Ruud outside unit
« Reply #6 on: May 24, 2009, 05:05:36 PM »
It won't work. the motor will run hot. If you need a 3 mfd a 5 mfd will be too much 440 can replace a 370 but 370 won't cut it on a 440.
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Offline ddw4170

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Re: capacitor replacement for Ruud outside unit
« Reply #7 on: May 25, 2009, 07:31:43 PM »
It is working fine, no noise that I can tell. I am going to get the proper replacement tomorrow. I have not been letting it cycle normally, I turn it on and off myself, so hopefully, there will be no permanent damage. I know these always come in three's, and it just happens that my fridge is now freezing up in the freezer side and the fridge side is just barely cold. All the fans are working as far as I can tell, but I have an inch of ice in the bottom of the freezer compartment. I don't have a clue yet on this, just popped the cover off an hour ago to check the fan in the freezer, seems ok. I hope the next one is something easy!

Thanks for your help!!
DDW

Offline Icehouse

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Re: capacitor replacement for Ruud outside unit
« Reply #8 on: May 26, 2009, 07:20:39 AM »
 :) Replacement Rules
For Capacitors

1. The voltage rating of the replacement capacitor must be equal to or greater than the original capacitor, never less. Example you can use a 440VAC rated capacitor to replace one rated at 370 VAC, however you cannot use a capacitor rated at 370 VAC to replace one rated at 440 VAC.

2. The microfarad rating of a run capacitor may vary plus or minus  10 % of the original run capacitor.
  
 
3. The microfarad rating of a start capacitor must be equal to or
    no greater than 20% of the original capacitor.

4. When wiring capacitors in series, the total capacitance shall be  less than the smallest capacitor. The formula is CT= 1/C1 + 1/C2.
  

5. When wired in parallel, the total capacitance shall be the sum of  all capacitors. The formula is CT= C1+C2
« Last Edit: May 26, 2009, 07:23:16 AM by Icehouse »
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Offline JWWebster

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Re: capacitor replacement for Ruud outside unit
« Reply #9 on: May 26, 2009, 07:01:37 PM »
In other words it is possible to add a 5 mfd cap to a say 20 mfd cap to make up a 25 mfd cap. Put a jumper between the commons and tape em together.
May the hinges of our friendship
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About the icons: The beer is tip link, if a tech saves ya some money buy em a 6 pack. The small green square=personal message. The green dot is a link to my web page on appliance repair and other general BS I love to post. The letter sends me email.
I love fan letters! LOL

Offline Icehouse

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Re: capacitor replacement for Ruud outside unit
« Reply #10 on: May 27, 2009, 12:07:15 PM »
 O0
NATE, NCCER, PHCC,HVAC Certified Instructor
Member RSES, US Army Refrigeration Specialist(Retired), Former Refrigeration Teacher NYC Board of Ed.
a tragedy has happen to me : http://web.me.com/zenzoidman/Bobice/

 

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