contactor replacement and capacitor help


Old 03-14-07, 06:23 PM
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contactor replacement and capacitor help

Hope to get some help. I noticed my compressor was not shutting off today when the ac went off. After some quick research I found it was from the contactor. I tapped it a few times with a screwdriver and right now it is working properly. I still want to replace it, but am concerned about the capacitor being they hold a charge. What do I need to know when replacing the contactor?

And while I had the cover opened I noticed a little puddle of some kind of clear sticky stuff right below the capacitor. Heres a picture of it. It's hard to see the liquid, but it's on the round thing right below the capacitor. I did not see anything coming from the capacitor, it appears completely dry all around, so maybe it's just silicon or something to protect the leads?
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Old 03-14-07, 09:11 PM
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I cant tell what you have there. If out of the capacitor or not. But to change out that relay turn the power to the unit . If you think the capacitor will get you. After the power is off. Take a big screw driver with a good insulated handel and short across the the two stabs on the top of it and then its killed to work on. That relay you have there looks like one that just kills one leg to the compressor. So if you go into the unit there be sure the power is off to it. Even if the compressor is not running and the relay is open. There is still 110V down in there
Old 03-16-07, 08:24 PM
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There is a special recommended procedure for discharging a capacitor, it involves a resistor hooked between the capacitor posts, 2 ohms I think but not sure since I never done it that way. I use my Fluke 16 multimeter to discharge them, it automatically discharges thru the meter when the leads are applied. But as Ed said the simplest thing is to simply short between the capacitor tabs with a insulated screwdriver. The reason they want you to use a resistor to do this is that it bleeds the current off gradually preventing the capacitor from exploding. So be sure to wear your PPE (Personal Protective Equipment in this case OSHA approved protective eyewear long sleeves and dry leather work gloves) when performing this type of electrical work as you may find your self covered in capacitor blood and you sure dont want it in your eyes or on your skin. That service call for a tech might just turn out to be a good deal after all if you do not take proper precautions. Now realistically the little capacitors found on most residential units would not make much of boom or spew much blood so the possibility of serious injury is remote but you should be aware of the risk anyway. Have a good day and DIY careful man.
Old 03-25-07, 09:15 AM
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Contator amps

Another question. My currect contactor is a 25 amp, would a 35 amp one cause any problems? Thanks for your help.
Old 03-25-07, 11:54 AM
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Actually the 35amp is a better contactor it can hold up to 35 amps instead of 25 amps.
The other thing you need to look at is control voltage for the contactor should be 24v.
Old 03-25-07, 12:22 PM
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couldn't see the "clear sticky stuff" you were referring to. The cap should have a small hole in the business end with what looks like some sort of filter material init. If the cap gets over heated, fluid will be expelled from that opening.

caps aren't very expensive and if you have doubts or concerns aboout the cap, I would go ahead and replace it. I saw nothing else that would expell any "clear sticky stuff" in yourr picture.

The other thing that comes to mind is the potential relay (that doesn;t mean it has the potential of becoming a relay, it is controlled by a difference of potential on 2 of it;s inputs. just a bit of electrician humor).

If the potential relay is not opening when it should be, that would cause the start cap to stay in circuit and that will overheat the cap and cause it to expel fluid., hence the fluid by the cap, maybe.

amp rating of contactors; bigger is better. simply means it can carry more load. not a bad thing.

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