AC keeps tripping breaker

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  #1  
Old 06-22-09, 08:18 AM
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AC keeps tripping breaker

I have a Carrier Unit, model 38EVG036310, approx. 3 years old, starting Friday afternoon, the breaker to the unit tripped. I turned off the themostat, reset the breaker and after about 2 hours it tripped again. I could hear the blower fan from the furnance running but the temperature in the house would never reach the temperature set on the thermostat. When I turned off the thermostat the fan would stop. So I reset the breaker again, then turned the thermostat on set it at 75 and the unit ran for another 2 hours. I trhough the thermostat had a short, so I change the thermostat and also changed the 30 am breaker in the box. Started the unit up again and this time it ran for about 6 hours and then tripped the breaker again. I then chekced the low voltage wires running along side the unit, did not appear to be any problems so I reset the breaker agian, same thing, runs for 4 to 5 hours and then trips breaker. Any direction will be greatly appreciated. Thanks
 
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  #2  
Old 06-22-09, 10:32 AM
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I'm new but experiencing a similar problem. About once a day, the circuit breaker connected to the outside AC unit trips. This seems to usually happen during the hot part of the day. My unit will run for hours, and then all of the sudden trip.

I searched the forum and other web pages and found the following common suggestions:

1. Check the amperage draw on the outside unit to see if it is overloading the breaker.

2. Check for shorts.

3. Replace the breaker.



I had a AC tech come out and inspect the unit. He said it was drawing the correct amperage and he did not find any shorts. He advised I replace the breaker. We checked the temperature of the breaker while the AC was running and it was a few degrees warmer than other breakers, but not noticeable to the touch. I replaced the breaker with a new one, but this did not fix the problem. Where should I go from here? Also, would you advise I seek help from an electrician or another AC tech?

Other info: unit is 3 years old, it's been very dry outside lately, I cleaned the coils recently

Thanks!

Matt
 
  #3  
Old 06-22-09, 11:11 AM
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thanks, I did replace the breaker, I will try #1 and 2, how did you fix your unit
 
  #4  
Old 06-22-09, 01:09 PM
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You may want to wash out the condensing coil with a water hose, preferably from the inside out. Also may want to have the freon checked. Does the ac cool at all when it's running?
 
  #5  
Old 06-22-09, 01:53 PM
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I did wash out the coils, but it didn't seem to change anything.

The unit is cooling great when its running - feels nice and cold - can go from 84 to 78 in a reasonable amount of time (maybe an hour or two).
 
  #6  
Old 06-22-09, 02:02 PM
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We have to different people posting similar problems. What works for one may not work for the other.

Hey Mod...these need to be split....
 
  #7  
Old 06-22-09, 06:19 PM
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both posters

1. check the breaker size against what the nameplate on the unit calls for

2. make sure all wire connections are tight

3. your units have copper wire right? what size?

4. babysit the units and see if the the fan motor [outdoors] is stopping on it's own

if the breakers stay on for several hours before tripping, it's not a short and it's not the thermostat.
 
  #8  
Old 06-23-09, 05:58 AM
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1. check the breaker size against what the nameplate on the unit calls for
Did this with the AC tech, the breaker size is correct

2. make sure all wire connections are tight
I made sure the connections were good in the breaker and the AC tech examined the outdoor unit

3. your units have copper wire right? what size?
Yes copper wire. Do I just measure the diameter? Bare wire or with the insulation? Also, are you talking about in the outdoor unit or in the breaker box?

4. babysit the units and see if the the fan motor [outdoors] is stopping on it's own
Do you mean to see if the unit will stop running on its own vs it only stops when the breaker trips? I know the unit will come on and off several times before tripping the breaker.
 
  #9  
Old 06-23-09, 06:39 AM
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1. sounds good BUT read the unit nameplate it will say maximum overcurrent protection and minimum overcurrent protection. What are those numbers?

2. examined outdoor unit? what about tightening the connections? How does the bussbar in the panel look? No evidence of overheating or burning?

3. the cable that goes from the breaker box to the a/c unit. On the unit nameplate there should be a minimum circuit ampacity number. What is that number? The cable will have a number on it like #8 or #6.

4. I've seen units with worn fan motor bearings that will run for a long time then the fan motor starts to overheat and shuts off on it's internal protector. next thing is the compressor draws high amps and could pop the breaker. The only way I've been able to fix them is pull up a lawn chair and observe. Frankly if it will run for hours it's more related to the brealker and wiring than the fan motor. I'm also wondering if after running for hours the compressor may have a hard time starting or if the power company voltage is a little low because everyon's a/c is going flat out on HOT days.
 
  #10  
Old 06-23-09, 08:24 AM
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daddyjohn, thanks it looks like both of us (sharky981 and imsuppermatt) have the same problem. I spoke with my AC guy this morning and he suggested I change the breaker to a 40 amp even though the system suggests 30, what are your thoughts?
 
  #11  
Old 06-23-09, 08:40 AM
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I did #1 and 2 as for 3 there is a cooper wire running from the breaker box into the ground, I don't see one from the unit to that wire unless it is connected underground. It's been running for about 1 1/2 hour upstairs is getting cool I will monitor it over the next couple of hours to see what happens and let you know. Thanks
 
  #12  
Old 06-23-09, 03:04 PM
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1. can get these for you - the tech read them and everything i saw was working within the correct limits

2. the tech unplugged and reattached seemingly every connection. Neither of us saw any evidence of burning or overheating. What is the bussbar and which panel is it in?

3. will check this

4. I can tell when the fan stops, but how will I know if the fan has stopped and the compressor is still running?

Thanks for your help!
 
  #13  
Old 06-23-09, 03:38 PM
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Ackkk I hate 2 problem on the same thread....anyway..

No..don't increase the breaker..its sized to the wires and the unit, per the manufacturers installation instructions. An A/C tech can measure the running load going to the unit.

It's 3 yrs old sharky...invest some money in a service call if you haven't already, with an authorized Carrier company. If you do things like upping the breaker and something happens..bye-bye warranty.
 
  #14  
Old 06-23-09, 05:08 PM
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sharky- GG is right on; do not upsize the breaker without checking things out first. Read the label on your unit, it should say minimum overcurrent protection and maximum overcurrent protection as well as minimum circuit ampacity. What are those numbers and what size wire goes to your unit, #10, #8 or#6? It will be written on the cable sheath. BTw- are you indicating that there is no shutoff switch at the outdoor unit?

supermatt- the bussbar is what the circuit breaker plugs into in the main panel. Understand that I am talking about the fan on the outdoor unit, not the fan that circulates air thru the ducts. Here's a common scenario with a marginal fan on the outdoor unit- the unit is runnnig cooling the house when all of a sudden the fan on the outdoor unit shuts off. howver the compressor continues running and it starts to sound louder and louder and like it's laboring This goes on for a minute or two and then the breaker trips. That's what I mean for you to monitor and the only way I know how is to pull up a lawn chair. However, the motor will usually stop in an hour or so.
 
  #15  
Old 06-24-09, 01:14 PM
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thanks I did not up the breaker, had another AC person come out late last night he took readings and said the compressor is shot, said he is getting a ground at the compressor and what is tripping the unit is the compressor is not gone yet but almost there. He says as the unit tries to cool the house it will only cool it to a point before the compressor shuts down and then trips the breaker. the unit was installed 3 years ago and there is a 5 year warranty on parts, he said he need to replace compressor, capacitor and dryer. Does this sound right?
He also said he has to drain the freon and install new freon, not the recaptured freon. I just had freon added approx. 3 weeks ago. Is this true? s
Since parts are under warranty I am just paying for his labor. just want to make sure he is not taking me to the bank. Any advice would be greatly appreciated. Thanks
 
  #16  
Old 06-24-09, 01:20 PM
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Sorry- a ground at the compressor would trip the breaker right away. How many ohms to ground did he read?
 
  #17  
Old 06-24-09, 01:34 PM
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I am not sure how many he read, he just called me over and placed the meter on the wire and it starting buzzing, he told me the buzing sound indicated the compressor was grounding. I thought a ground would cause the breaker to trip immediately. Is there any truth to his theory that the compressor is not fully blown yet which is why the unit would run for some period before shutting down the breaker?
 
  #18  
Old 06-24-09, 01:44 PM
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Good question. He used a continuty tester? He didn't read actual ohms? Did he have the wires disconnected from the compressor motor teminals? If he was reading a wire going to the compressor and not at the compressor motor terminals isolated from the wiring, how does he now it's not simply a chafed wire? If my former students did that the extraction team would have to called in. Time for you to try moron #3.

BTW- you didn't mention that refrigerant was added. Where's the leak?
 
  #19  
Old 06-25-09, 09:12 AM
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yes he did have the wires disconnected from the terminal.

Small amount if freon was added when the other unit had some added. The other unit does have a leak and I will have him check and possibly fix it.
 
  #20  
Old 06-25-09, 10:10 AM
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Do you know exactly where he placed the meter leads? Even if the compressor is in warranty, it might be good to get a second opinion.
 
  #21  
Old 06-29-09, 06:55 PM
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I had another company out over the weekend. They said the compressor is over-drawing because it is pulling 12.3 amps and is rated to 14. They said it should be drawing half of the rating. Is this correct?

They recommended replacing the compressor which is under warranty which might get everything working or completely replacing the outdoor unit.

Any advice is appreciated.
 
  #22  
Old 06-29-09, 08:08 PM
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Maybe it's time to call a third moron er.. technician. It can draw all the way up to the rating. What do they think the rating is for? Someone please explain to me how a compressor can run for hours and then all of a sudden it's bad? You never did get us the a/c unit namelate info, the wire size [beginning at the panel], and the breaker size. I still think your breaker and wire are sized at the low end of the spectrum.
 
  #23  
Old 06-30-09, 07:19 AM
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sorry for being out of the loop the last couple of days, AC man came on Friday and replaced the compressor, took him about 3 1/2 hours, he drained line, replaced the dryer, replaced the condensor and compressor, he cleaned outside coil pressure tested the unit and used a computer to refile the unit with Puron. I don't think the unit has cooled the way it is cooling ever. I've been in the house for 3 years and in the past I had to take thermostat down to 74 just to keep upstairs cool. The temp has not been below 78 now and it feels just as cool. Thanks for all you threads as they have helped me to become somewhat knowledgable about the AC unit.
 
  #24  
Old 06-30-09, 09:38 AM
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Yes, I've been lacking. I'll check the a/c unit namelate info, the wire size [beginning at the panel], and the breaker size when I get home.

A third technician came this morning. Told us we needed new evaporator coils, because they are mismatched (over-sized) with the 3.5 ton outside unit. I believe he said we had a 5 ton evaporator coil and since it was mismatched it was causing the system to overload. I sat around the AC last night hoping to catch it stop working to check the bad fan bearing theory, but it kept running fine - I'll still try and catch that one sometime.
 
  #25  
Old 06-30-09, 12:35 PM
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sharky- thanks for the feedback. I still don't buy the therory of a partially grounded compressor, but if your system is working, it's working. If it's cooling better than ever before, that kind of tells you something doesn't it?
 
  #26  
Old 06-30-09, 12:50 PM
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matt- 3 guys, 3 theories of the crime. Most of the motors I babysat went South in an hour or less. Overiszed coils hmmm. Unit is 3 years old? What's 3 years old? The whole system or only the outdoor unit? Did this breaker tripping occur last Summer? Have you had any other work done since then- Freon recharge or the like?
 
  #27  
Old 06-30-09, 01:03 PM
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It's a 3 year old townhouse, so everything is 3 years old.

The breaker had never tripped until a few weeks ago, and we've never had any work done.

When talking about the oversized evaporator coils with the smaller outside unit, one of the previous companies told me this should not be causing the problem. He claimed if the sizes were switched, so that the outside unit was much bigger than the evaporator coils, it would cause a restriction and possible failure.
 
  #28  
Old 06-30-09, 01:22 PM
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Each manufacturer has different combinations of coils/outdoor units for various capacities and the sensible heat to latent heat ratio. If this is a new problem then something has changed. My iinstinct is the breaker is sized close to the vest which is why I'm asking for that info. I always size at the maximum allowed breaker for those days that are hotter than design days.
 
  #29  
Old 06-30-09, 02:16 PM
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Just out of curiousity - if the unit does allow for a larger breaker, can I use the larger breaker without changing any wires or other electrical hardware?
 
  #30  
Old 06-30-09, 05:19 PM
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Yet another technician said we had should get a "start-stop" which delays the starting or something. He said he didn't see anything else wrong with either the outdoor unit or the evaporator coils.

After some research, I'm guessing he was referring to a "hard-start" kit.
 
  #31  
Old 06-30-09, 05:24 PM
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Ok, so the unit calls for a 20.2 A breaker min and 30 A breaker max. I have a 30 A breaker in the panel. This is the one I replaced a week ago. I pulled it out to examine the bussbar. The bussbar had a small amount of orangy grease on it. The grease did not have a smell. None of the other slots had this grease. Also, the bussbar had a little noticeable wear on it - it looked like something had been rubbing on it a lot - the others did not look like that.

I looked at the wire and could not find a number on it for the life of me - I'll google this and see if I can figure out the size.

More name-plate info:
Goodman - 13 seer
Model: GSC130421A A
AC VOLTS: 208/230
VOLTAGE RANGE 197-253
MIN CIRCUIT AMPS: 20.2
MAX CIRCUIT AMPS: 30
 
  #32  
Old 06-30-09, 06:01 PM
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It's probably #10 wire, it is copper, right? I hope they didn't use #12. Does the breaker fit tightly onto the bus bar? I can't recall ever seeing any orange grease [or any other color for that matter] on a bussbar. I wonder if it came from the new breaker? Does the bussbar look like it has been overheated where it the breaker plugs in? Any chance you can move breakers around in the panel and put the a/c breaker in a different slot? The third guy is probably talking about a hard start kit, not a bad idea but I would think if you need a hard start, the breaker would trip more often.
 
  #33  
Old 06-30-09, 06:07 PM
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The orange grease is normal. Some manufactures add a little dab (Siemens, HomeLine) to the breakers "jaws" so aid in installation of the breaker on to the buss bar. If you had a poor connection you would see pitting on the buss bar or breaker jaws.

If you have #10 wire, a 30 amp breaker, and all your connections are tight, I suspect your problem is not your electrical branch circuit but in your condenser. Likely a motor failing.
 
  #34  
Old 06-30-09, 06:28 PM
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Couldn't figure out the wire size directly - but there is a white, a red, and a ground, and it is copper. Measuring a single wire with the casing I got a diameter of .225".

The breaker does fit tightly onto the bus bar.

The bus bar does look different where the breaker plugs in. It's hard to see, but it could be some pitting. Neither the previous or the new breaker has any signs of overheating and I don't see any pitting on the breaker jaws.

I think I could move the breakers around to get the a/c breaker in a new place.
 
  #35  
Old 06-30-09, 06:53 PM
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The delay is a time delay on make or an anti-shortcycle time delay to insure 3 minutes between start and stops.If the compressor starts again before pressures equalize it could trip the breaker. I did have a 10 ton that I could only pick up the short with a megger. 2ND company said it was fine...reset it...posts shorted internally and blew up and out the posts.
 
  #36  
Old 06-30-09, 06:59 PM
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Use a delay on break not delay on make timer. yeah buudy- they make a heck of a mess when a post blows out.
 
  #37  
Old 06-30-09, 08:07 PM
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Originally Posted by imsupermattt View Post
Couldn't figure out the wire size directly - but there is a white, a red, and a ground, and it is copper. Measuring a single wire with the casing I got a diameter of .225".

TW,THHW,THW #10 wire is aprox .176 inch
THHN,THWN,THWN-2 #10 is aprox .164 inch

I'm assuming the wire is solid not stranded? It sounds like #10 to me.
 
  #38  
Old 06-30-09, 09:56 PM
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under the cover it was stranded - looked like pretty thick stuff - definitely thicker than standard romex
 
  #39  
Old 07-06-09, 09:05 AM
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I moved the breaker to a new location in the panel, and we also had the hard-start added. Additionally, the technician did some work in the attic, but my wife explained this to me and it wasn't too clear what was actually done.

Now, we've been running 5 days without tripping the breaker - so something we did worked.

Anyways, thanks for all your help guys.
 
  #40  
Old 07-06-09, 10:55 AM
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That sounds good! We appreciate the feedback, it helps others. Thanks.
 
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