A/C breaker tripping, but sllightly different symptoms


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Old 07-26-08, 08:59 PM
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A/C breaker tripping, but sllightly different symptoms

Hi:
I'm new, this is my first post.

I have a 5 tone central air cond.unit on the roof of my home. The unit was installed in 2002. Last summer the A/C started tripping the 30 amp breaker. Because the entire oanel was at least 30 years old I went ahead and had my electrician replace the entire panel and install a 40 amp breaker.

The same problem started happening this summer as soon as it started getting good and hot. I was reluctant to do this, but I allowed the electrician to install another panel with "Square D" breakers with a 50 amp breaker for the A/C. The breaker still trips about 3 times a day, but only after the A/C has run for at least 2 or 3 hours or more, It happens at varying intervals. The electrician has gone over his installation three times and can't seem to find anything amiss.

I called the company that installed the entire unit. At first their tech's couldn't ,and still can't find anything amiss on the A/C end. The tech thought that it "might" be the condenser fan motor, and installed a new one. This didn't cure the problem. My Electrician has run a temporary, heavy gauge line to the A/C, but I still have to reset the breaker 3 or more times a day. Today, both the electrician, and the A/C tech have decided that it's the Compressor. I would accept that except this whole mess has become one big guessing game.

When the tech replaced the condensor fan motor, he added about 2 pounds of refrigerant.

Being that a condensor R&R is a fairly expensive repair, and since both these guys have all ready cost me about $2500.00, I would really appreciate it if someone here might be willing to render an opinion.

I would rather have a new central A/C unit installed before throwing more money down the sink hole this has become. On the other hand if there is a possibility that has been over looked I'd appreciate anyone's input, as I would rather just repair the exiisting unit since it's only 6 years old.

Thanks
Cliff Harmon
 
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Old 07-27-08, 09:21 AM
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First

You might try and have the start circuit checked on the compressor (it may be weak or not able to overcome the individual circumstances of its present installed conditions (even if it is brand new) - It is a known fact that when compressors start, it is a huge draw of current up until about 80% of the running speed of that said compressor - If it is taking too long to get to that speed - it may overheat the breaker. Keep in mind if it is really hot outside, the head pressure will be high even when it is static (especially systems with expansion valves as metering devices). The compressor must start against this pressure.

Try what is called a hard start kit - It will help the compressor effiecently startup and get to that 80% running speed with less current and much faster start time.

Have the referigerant charge checked( by means of superheat and subcooling).
and check the outdoor coil for clogging, especially dual coil units. The dirt and other substances get inbetween the dual coils and cant be seen by merely looking at the outside of the condenser.

Should cost about 250.00 to have the hard start kit installed. That is the best advise I can give you with the information you provided.
 
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Old 07-27-08, 02:36 PM
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A breaker should not be replaced with a higher rated one just because it trips!! It should match the specs on the A/C unit! The reason for the breaker tripping needs to be found, and the breaker replaced with the correct rating.
 
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Old 07-27-08, 02:42 PM
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Breaker size

Originally Posted by OregonYeti View Post
A breaker should not be replaced with a higher rated one just because it trips!! It should match the specs on the A/C unit! The reason for the breaker tripping needs to be found, and the breaker replaced with the correct rating.
Sorry, forgot to mention that as I wrote my synopsis of the corrected action - But... yes! Get the correct breaker size put back ASAP!

Good point!
 
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Old 07-27-08, 03:30 PM
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Does anyone here have any insight as to what the amp spike might be expected when a correctly operational compressor and fan kicks on by the cap(s), so one knows what to make of an amp reading taken at the outdoor unit, so one knows if a breaker has gone weak?, or, if there indeed is too much draw, at least at start up?

[Yesterday I had to change out my defective breaker to my electric water heater, as the 2-pole 20 amp breaker was heating up(getting hot, actually)/kicking out with only a sustained 16 amp draw(readitng taken off wire at breaker by an amp meter). The new breaker cured it and barely gets warm now.]
 
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Old 07-27-08, 05:15 PM
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Its called....

Normally there is about a 30-40 amp breaker for a normal non exotic condenser which will be identified as what is required for that unit on the condenser data plate. Here is an explination of the rest!


Lock Rotor Amps - LRA. (varies alot but about 180-200 amps) for a 3 -5 ton - Its expected draw is on the data plate of each condenser. Normally this amp draw (or spike as you call it) does not affect the breaker until it is "Untimely". There are many reasons for an untimely start of a compressor. I mentioned it in the post below.

I think pretty much if a breaker trips during FLA= normal running amps (varies alot but about 12-24 amps for 3-5 ton) also located on data plate - the connections at each point from the hook posts of the breaker panel (Where the actual input of the breaker is on the power bars of the electrical panel) and every connection inbetween, to the compressor terminals themselves need to be checked for tighness and burns. If they are all good - Change the breaker.

If the breaker trips during startup - Check the existing capacitors ( run and... start:if it has one) If they are good continue to checking all connections as in the first paragraph above - If all is good, a hard start kit for the compressor should be installed. The effiency of start will change drastically and should correct the tripping of the breaker.

This is my understanding of the problem - There might be other opinions or further elaboration in detail by others.
 

Last edited by The Real Deal; 07-27-08 at 05:34 PM.
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Old 07-27-08, 05:35 PM
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Real Deal, do you do a lot of commercial or work on old equipment? The reason I ask is that 12-24 amps is what I see in older or cheaper equipment in the 3-5 ton range

As you said, though, check the unit's data plate.
 
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Old 07-27-08, 05:39 PM
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Hi

I work/have worked on the latest and the oldest major commercial HVAC systems to tinyest latest and the oldest residential equipment available on the market today. 2-200 tons Air to Air - chilled Water - walkins reachins...u name it!...and so on - I have been to the top,bottom and all that is between

It was just an example so the reader could see the difference in LRA/RLA - The amps are as different from system to system as there are atoms in your finger.

Thanks! I am primarily a major commercial technician for now, but do alot of bailing out in the residential side for the company ie...(helping lessor skilled techs out of jams).
 
 

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