How to check capacitor?

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  #1  
Old 05-25-01, 02:58 PM
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What is the best way to check the compressor start capacitor?
 
  #2  
Old 05-25-01, 04:06 PM
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Buy a new one

The exact one,install it,and turn power on.If compressor starts you are all set.PDF
 
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Old 05-25-01, 06:08 PM
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take an Ohmmeter and on it's highest scale touchone test lead to each end of the terminals (while it's disconnected) your meter should rise then fall, switch sides with test leads, meter should rise and fall again, if you don't have a meter to check Uf rating you can use this formula

AMPS X 2650/VOLTS A.C.= uF RATING

BUT to do this you would need to cut up an extension cord plug it into the capacitor, use a clamp-on ampmeter to get the amps for the Formula, then measure the volts coming out of outlet to get volts reading for formula so then you take Amps times 2650 divided by volts, but you should probably not do that, I say you ran the compressor sooooo long without it cooling that the compressor either shorted out, or it went into overload (it's probably hot as heck)but you can also look at the capacitor and see if there is any buldges in it
 
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Old 05-26-01, 04:55 AM
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SADNTM

As I stated earlier.Take capacitor with you to a motor supply house.They will test old one.The cap testers we use will tell you the extact condition of it and also give you the MFD rating.If you are privy to or own a amprobe and volt/ohm meter you must cut the resister off of one terminal(if one is installed).An ohm meter is a good quick check,however when testing caps in the 500-600 MFD range you really need a cap tester.If exact replacement is not available make sure the cap is slightly under rated and not over rated.You can however go with the old series or parallel hookup.PDF
 
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Old 05-26-01, 05:08 AM
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Thanks guys

I got the fan running again by putting in a new start capacitor/relay power pack. Compressor still does not come on. Compressor has a start or start/run capacitor. Power is going in one side but not out the other which goes to the compressor, not constant power anyway. Will check for momentary start power when first turned on as soon as someone else gets up to give me a hand. Always like to have someone on hand when working on a powered system. Wouldn't like the kids to come out and find dear old dad doing the permanent dirt snooze out in the yard ;-)

Thanks for helping. I'm use to working on aircraft and cars, not HVACs.
 
  #6  
Old 05-26-01, 07:25 AM
HVAC Man
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Wow, you run across Capacitors in the 500-600 Microfarad range? what are those used for?, in my company, and school the biggest I ever seen is like 40uF. just wondering
 
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Old 05-26-01, 10:02 AM
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SADNTM

This forum does not allow any DAD to assume room temperature,and because it is so close to FATHERS DAY we must wait until afterwards.Glad to see you are using the buddy system.If you have visited this forum on a regular basis you realize we ALWAYS stress power off.I hope our threads have helped you clarify your problem.I also work on aircraft.Aircraft a/c that is.It gets a little scary on a prop plane when in order to charge the system,the props are running at a high idle,your back is against the wing so you don't get blown over.THE ONE THING with planes I never do is remove a screw from any panel.I tell the pilot or owner that is their responsibility.

HVACMan....I do a lot of work on refrigeration.High torque compressors need the extra boost to get rolling.The lowest MFD rating I carried was 88-108 for a start cap...Most 1/4 and 1/3 HP refrigeration compressor use a 189-233 start cap...If you ever get stuck in an emergency don't forget the series/parellel cap arrangement.40 MFD is usually run cap territory.PDF
 
  #8  
Old 05-26-01, 11:21 AM
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Unhappy Thanks for the help guys

but the compressor is shorted out. Have to wait till new system is installed next weekend to cool off. Have a great Memorial Day weekend, and remember why we have the holiday.
 
 

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