# condensor breaker tripping



## AustinDB (Sep 11, 2006)

I have a 60a breaker that occasionally trips. I'm going to remove and reinstall the breaker in search of a bad contact then pull off the cover of the unit and check for connection issues. This unit had issues last year when the startup cap fried and was replaced. 

are there any other items to check for? the unit hasn't been charged for as long as I can remember-but if it were overcharged, is that a possible source for over-current draw?


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## 480sparky (Feb 1, 2009)

Check for a bad capacitor. Also check to see the coil fins are clean and clear of debris.


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## Baltar (May 21, 2010)

What size unit is it and make and model #. Did you check for low voltage/do they have brownouts in the area. Does it have a starting/potential relay to disconnect the start cap? maybe it is sticking? Check the amp draw on startup.


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## AustinDB (Sep 11, 2006)

fins are clean-good airflow. I recall when the service was done last year the hvac tech put in a cap and it stopped working a day later...looked at the unit and read the cap requirement then went out to get the correctly rated cap :-( since then it was working properly. 

I do recall something that struck me as a little odd, the breaker is a 2 pole 60a and in the same breaker box are 3 pole breakers for the other condensor units. It's a 3 phase service site-if someone can help me to understand that would be nice


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## Baltar (May 21, 2010)

You can take 2 legs/hot off a 3 phase service and get single phase power. It may be a single phase unit. 3 phase units do not use capacitors from my memory.


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## beenthere (Mar 5, 2009)

Post the brand and model number of the unit.


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## AustinDB (Sep 11, 2006)

argh...I'll have to drive over tomorrow and get the model number from the unit. thanks for the info on the single/three phase wiring. there was definitely a capacitor on the unit-when it was burned out it wouldn't start the fan....


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## 480sparky (Feb 1, 2009)

Be sure to get the ALL the nameplate data:

Minimum circuit ampacity, Maximum OCPD, LRA, FLA, all that good stuff.

Oh, yeah, and the wire size............


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## griz (Nov 26, 2009)

72chevy4x4 said:


> I have a 60a breaker that occasionally trips. I'm going to remove and reinstall the breaker in search of a bad contact then pull off the cover of the unit and check for connection issues. This unit had issues last year when the startup cap fried and was replaced.
> 
> are there any other items to check for? the unit hasn't been charged for as long as I can remember-but if it were overcharged, is that a possible source for over-current draw?


Just my 2 cents, probably gonna be faster & cheaper to have a* professional* HVAC tech check it out. Too many variables.


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## AustinDB (Sep 11, 2006)

I looked over the condensor unit and breaker today. measured current draw w/ a clamp on and it was pulling ~27-28A continually (103F weather!), below specs on the unit, a Ducane AC10B60 (5 ton). The panel on the side of the Ducane says to use a max 60A breaker...inside in the old Cutler Hammer box sits a 50A breaker. 

From memory, I think rated current draw for the compressor was 28A, the fan wasn't listed. When installing a breaker on a new unit, do you always put the max size breaker? If so, swapping out the 50A for a 60A may fix this, but I'll have to check the wire size. Wire run is less than 30' to the unit from the box.


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## flashheatingand (May 3, 2008)

You may be having a hard start problem with the compressor. Turn off the unit, put the clamp on one of the lines (preferably the common) and then turn on the unit. What did the meter max at upon startup? As griz mentioned, there are a lot of variables. So, it really is hard to say. It's just one thing that comes to mind.

I know several people would say get a hvac guy. But, it sounds as if this is something you want to try to figure out on your own...good luck.


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## 480sparky (Feb 1, 2009)

The only way to get a good read of the start-up current is with a recording-type meter. Just looking for the largest number that shows up is not going to even get you close.


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## AustinDB (Sep 11, 2006)

I did check startup current readings by switching on the disconnect box at the unit and they were within 27A-28A and then observed the unit for 10+ minutes. 

what is the characteristics of a dirty line filter/drier?


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## bwalley (Jan 7, 2009)

72chevy4x4 said:


> I did check startup current readings by switching on the disconnect box at the unit and they were within 27A-28A and then observed the unit for 10+ minutes.
> 
> what is the characteristics of a dirty line filter/drier?


Your starting amperage will be higher than your FLA, it happens quickly and you probably missed it.

What size is the wire feeding the condenser?

Once a breaker starts tripping, they get weak, but if it is only pulling 28 amps, a 50 amp breaker shouldn't be tripping.


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## 480sparky (Feb 1, 2009)

72chevy4x4 said:


> I did check startup current readings by switching on the disconnect box at the unit and they were within 27A-28A and then observed the unit for 10+ minutes.
> 
> what is the characteristics of a dirty line filter/drier?



Does your meter have the ability to record & display the start-up current, or are you just watching the display?

If it's the latter, you will never see the true start-up. The start-up current usually lasts only 5-6 full cycles (1/10th of a second), and most meters only refresh the display 2-3 times a second (1/2 - 1/3 sec.) The odds of you actually seeing the real start-up current is slim and none, and slim's left town.


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## AustinDB (Sep 11, 2006)

thanks 480-I meant to mention something about your great comment last post. my meter updates 2x's / second, so it's not getting the initial-intial startup. Is there a handheld that does this? 

can the condition of the cap effect the startup current?


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## AustinDB (Sep 11, 2006)

what if the lineset was improperly sized from the initial installation, that is being too small, would that cause increased load issues? Have not been able to find the Ducane install instructions on this older unit, but on one of their newer units runs of 75' should use 1/2" and 1 1/8" lines.


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## beenthere (Mar 5, 2009)

What model Ducane is that, that they want a ½" liquid line if its a 75' line set.

Generally, you would need to be a 6.5, 7.5 or larger unit for a ½" liquid line. 

While the size of the line set can effect compressor amp draw. It would generally be an extremely undersized line set to trip the breaker.


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## AustinDB (Sep 11, 2006)

It's a Ducane AC10B60, 5 ton unit. AC guy will be out tomorrow...guess they have been busy with the "AC is out" calls.


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## beenthere (Mar 5, 2009)

Check to see if the indoor unit has a TXV. If so, you need a hard start kit on the condenser.


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