Outside unit trips breaker


  #1  
Old 09-28-05, 06:09 AM
decyph3r
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Outside unit trips breaker

Ok, here's my second post for the day, concerning my downstairs AC. Since the beginning of this summer, my downstairs outside unit has been randomely tripping the breaker. It "appears" to occur most often on days that it rains or the sprinklers run. After taking off the panel though, I have found no evidence of water intrusion though. It does trip at random other times however. Attempts to wash down with hose have not caused unexpected failures, so I'm at a loss as to why it mostly happens on days where the unit gets somewhat wet (2am .. not much heat outside).

I did replace the breaker, which was fried on one side badly. I did clean up the contact on the tbar in the breaker box, which was not damaged.

The "fuse", well not really a fuse, just a connector which plugs into the outside box next to the unit does appear to show some frying of the contacts. Should this be replaced, or is cleaning up the contacts OK for this as well?

I'm afraid if I clean up those contacts, my problem will still exist? I've had one AC person out to look at the problem, and all he wanted to do was sell me a hard start kit. Is there anything internal to the AC unit which could cause all of these contacts to fry?

This unit is Lennox as well, and compressor/capacitor in outside unit are less then one year old. Unit cools fine while running.

Thanks.
 
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Old 09-28-05, 07:23 AM
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if this unit is less than one years old, Call back the installing dealer for warranity work.
 
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Old 09-28-05, 07:24 AM
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"Fried" contacts usually means bad connections, which means lots of heat. Damage on the pull box contacts seems unusual and I wonder if there isn't a loose connection on one of the wires that's causing enough heat to damage the pull. Turn off the breaker and open up the pull box on the side of the house. Take the inside cover off to expose the connections and check to see if there is any damage. Replace anything that shows heat damage of any kind. Please let us know what you find.

Doug M.
 
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Old 09-28-05, 07:46 AM
decyph3r
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Doug - After closer inspection, here's what I see.

1. All wiring and wiring connection points appear to be good (in pull box and in unit).

2. Contacts are slightly fried in pull box (not all, just 3 out of 4). They aren't even close to as fried as the contacts were on the breaker I replaced though.

3. Contacts on black unit that all the wires plug into appear to be fried. Sorry for not knowing the name of this piece. It's roughly square in shape, and all wiring inside the unit seems to terminate on different contacts on this piece. It has a coiled copper coil on it's underside. Sits right next to the capacitor.

Last time I saw fried contacts that looked like that, it was on a relay for a pump, and the relay had to be replaced (contacts are severely scarred, with severe divoting, and a burnt look). Sounds like this might be one of my problems?!
 
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Old 09-28-05, 08:12 AM
decyph3r
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Update: I have posted some pictures of the areas I am seeing "burn" problems in. Problem locations circled in red.

http://www.gruuv.com/decyph3r/

1.jpg = The black unit I don't know the name of
2.jpg/3.jpg = The pull box

As for the pull box locations, both circled areas appear to be circle shaped contacts that "close" to complete a circuit. They are both fried around the edges, and the contacts themselves are fried and divoted. - Thanks
 
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Old 09-28-05, 08:30 AM
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Okay, doesn't look like a problem with loose connections... but once the main problem is fixed, the pull box needs to be replaced so it doesn't become a problem later. They're cheap. The contactor shown in your first pic. is probably a symptom of the problem too. It may be fine, but has obviously seen some overloading. Again, too cheap to leave possibley damaged. Back to looking at the unit itself... It's obviously pulling excessive power, probably at start-up and is running close to the capacity of the circuit so the breaker gets hot in the beginning, never has a chance to cool down and trips randomly while running. That hard start kit is sounding like it might not be the wrong idea. Any opinions from the experts?

Doug M.
 
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Old 09-28-05, 09:41 AM
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Id get a Amprobe on there first thing and see what is what. Check the capacitor there and see if its up to par. If the start amps are high and the run amps ok then go for a start kit on it. Get a full start kit one with a potential in it. Also put a new contactor in it. Dont mess with the burned out points.

ED
 
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Old 09-28-05, 09:57 AM
decyph3r
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Ed - If I'm not mistaken the thing skyrockets on the AMPS at startup... something like 130-140 maybe higher. It does level off between 40 and 50 though, with the breaker/unit being rated for 50.

1. Obviously it's start AMPS are way higher then they should be. I can't believe this is "normal" operation though. It is a 5ton unit though, and it's flibbin hot down here in the Dallas area these days... so who knows. AC guy seemed to think these start values were normal, but that it shouldn't cause the breaker to trip. I'm guessing there is some electrical knowhow 101 in here somewhere though, and common sense got lost in translation.

2. Is it safe to be running close to the max 50 it's rated at? Is this at least expected?

Your desciption seems to hit the nail on the head, and confirms what the previous AC guy told me (possibly start kit needed).

Btw: What's a potential? How can I make sure the start kit has one?

Thanks.
 
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Old 09-28-05, 10:55 AM
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My 5 ton unit pulls a lot to start. Quite a noticeable split second dim of the entire house, but I've never put a probe on it to see how much, and my 50 amp breaker has never tripped. 130-140 amps is asking a lot of all the parts involved. If the duration was long enough and load was high in the rest of the house, I would think this might pull out the main on occasion. With all the stressed parts, your compressor might be pulling more amps for longer because of the poor connections. Get the hard start kit in, replace all the worn out parts and let us know what happens.

BTW: If I'm not mistaken, a hard start kit with a potential relay, will sense the speed of the compressor and kick out when it's not needed. There are also electronic hard start kits that use a different method to kick out, but I think Ed is warning you that they aren't as reliable. Ed knows what he's talking about.

Quick check of the radar shows our "cold" front just hitting the panhandle. Might get into the 50's tonight - Forget the A/C, it's time to fire up the furnaces!

Doug M.
 
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Old 09-28-05, 03:03 PM
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When you put a starting assist kit on a unit. Yes it helps some. Like you flip it with your finger and it runs. Now when you put a full start kit on a unit, not only do you have the potential relay there .But it also has a OLd Reliable capacitor. Some times up to 3 or 400 MFD. So you see thats not just a finger to start thats a big kick in the A**
Another thing, like years back wont say the company. But we sold lots of AC and had them in when bang almost every one started to pop fuses. We had h***. Did get the company to look at it and found almost all the new compressors had a mild short in them. They sent down start kits for all and we put them on. Everything worked out just fine. You see that a compressor has a start ,run, and common in it. Now with the full start kit with the potential relay it drops the start out after its up to run and this cut the little short off. Boy the things you dont learn in school

ED
 
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Old 09-29-05, 06:35 AM
decyph3r
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Ok.. got an Ampmeter on this unit. Here's the details.

134 Amps at startup
26.4 Amps running (it's RLA is 25 Amps)

It's only 60 degrees outside, and I'm pegged!!

Sure appears to be general over-amping to me. Are we still sure a hard start kit is the fix? Appears to me that my compressor (which was replaced 2 months ago), isn't doing so hot. Suggestions? Get the compressor replaced again (this time on Lennox's $$$, since it should be within warranty).

Thanks.
 
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Old 09-30-05, 12:55 PM
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Id get on LENNOX . You dont have to put up with that.Not there but Ill bet if you pull all the wire off the compressor and OHM it out you will find a WEAK short in it.

ED
 
 

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