# AC starts/stops



## Doc Holliday (Mar 12, 2011)

rhouston said:


> my outside condenser starts and stops. I turn the ac on and you can hear the unit try and start, the lights dim a bit and then it stops. The circuit breaker doesn't trip. the motor blade is free, and the capaceter seems to be fine, no bulges or oil. The unit is 11 years old and had been working fine. I turn it off and on alot because of leaving during the night and wanting to save $$. any suggestions would be awesome.
> 
> Thanks


 
seems fine and testing it to be certain it is fine are two entirely different things. I've replaced fourteen (14) capacitors this past week alone, all compressors trying to start.


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## Marty S. (Oct 31, 2009)

Good call doc. I find maybe 2-3 out of 100 dead capacitors show bulging or leaking. Fourteen dead caps this week sounds like business picked up down there.


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## Doc Holliday (Mar 12, 2011)

Marty S. said:


> Good call doc. I find maybe 2-3 out of 100 dead capacitors show bulging or leaking. Fourteen dead caps this week sounds like business picked up down there.


 
I worked on my Trane 6 ton 13 SEER 410-A rtu commercial retrofit (with all new metal duct, externally wrapped R-6) until 3 a.m. this morning. That job is killing me and taking away from service calls.

Business is booming, I need to clone myself.


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## rhouston (Jun 2, 2011)

*Fan works*

im not in houston, im in NC. I turned the ac on and then pushed the fan to get started, and it started to run, so I know that capaciter is bad, the trouble now is no cool air is coming out of the vent, do i need to replace the capaciter for the condenser also?

thanks


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## Doc Holliday (Mar 12, 2011)

rhouston said:


> im not in houston, im in NC. I turned the ac on and then pushed the fan to get started, and it started to run, so I know that capaciter is bad, the trouble now is no cool air is coming out of the vent, do i need to replace the capaciter for the condenser also?
> 
> thanks


 
I'm a bit confused as to which motor we're talking about. If the cap is bad for the compressor which is outside in the condensing unit then your compressor will not start so you won't have cool air. That is one of multiples of possibilities of why you have no cool air.

Which fan did you push by hand? Ack.


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## rhouston (Jun 2, 2011)

I pushed the fan on the outside unit to get it going, where as before it was trying to start and made a buzzing noise. I pushed the fan and it was running and air was blowing inside, but it wasnt cool. What does this mean, I thought there was a capaciter for the fan motor and one for the condenser.


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## voneckner (Jun 4, 2011)

There can be two capacitors but not always. If there are two its one for compressor, and one for fan. The lack of cool air could mean you need to clean the condenser and the evaporator, and verify air flow, before you even think of adding gas.


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## voneckner (Jun 4, 2011)

Also you said the capacitor seem fine, did you verify this with you multimeter.


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## rhouston (Jun 2, 2011)

the air flow is fine, I can turn the fan in the house on np, so I can get the fan outside started and it runs, just no cold air. Can I safely say this is an issue with the condensers capaciter?


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## voneckner (Jun 4, 2011)

Check the resistance on the capacitor. Is it within the required amount, writen on it, (ussually + or- 10%). Also did the unit alwasy dim the lights when it started, if so a hard start kit would help eliminate that. If you verify the capacitor is fine, you have eliminated one more thing.


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## jerick (Jun 7, 2011)

*ac probs [email protected]#$*

My instructor always said "think simple stupid" ( not implying anything). The filter or maybe one of the capacitors-if there more then one.


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## Doc Holliday (Mar 12, 2011)

rhouston said:


> the air flow is fine, I can turn the fan in the house on np, so I can get the fan outside started and it runs, just no cold air. Can I safely say this is an issue with the condensers capaciter?


You can safely assume that the dual run cap which runs both the fan and the compresssor is not running the COMPRESSOR as the common might have been going out on the capacitOR and you need that common for the fan circuit. The common on a dual run capacitOR is shared for both the compressor and the fan so if one side a dual run capacitOr goes out then it's safe to assume that nothing is going to really work. 

The only way to know for sure is to either test the capacitOr or replace it. 
What we need to know at this point is what is going on with the compressor, not the fan.

Is the compressor running or not? If not and the fan is barely trying to spin than more than likely your capacitOR is bad. 

Start there and come back.


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