A/C unit won't start, but seems to be getting power.


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Old 08-31-08, 09:33 PM
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A/C unit won't start, but seems to be getting power.

This is a very old outdoor Sears unit. In the beginning of summer, the compressor would not work. I put in a hard start kit, and A/C worked fine all summer. Today (mid 80s - tstat set to low 70s) the unit quit working and won't start. I replaced both outside fuses.
Unlike at the beginning of summer, I do not hear the compressor trying to start up and the outside fan doesn't turn on. I can hear that power is getting to the unit when I switch to "on" or "auto" at the tstat, but nothing happens.
The blower turns on inside, so I don't think it would have anything to do with a reset button on the motor? I don't even know if there is one, as I could not really get my hand in there very well.
I think I overworked the unit today, but it has been shut off for hours and still won't start.
After more research, I hope I just need another new capacitor. I didn't realize the capacitor runs the fan and the compressor. I was confused why neither is working this time when fan worked, but not the compressor at the beginning of summer.
 

Last edited by allansrule; 08-31-08 at 11:10 PM. Reason: After further research
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Old 09-01-08, 07:09 AM
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If the fan and compressor is not running, then you need to take a meter to check your power to be sure you are getting 220volts to the contactor in the unit itself, if nothing, then trace back to the disconnect switch, or main panel if you are not reading 220v.

YOu do hear the contactor clicking right?
 
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Old 09-01-08, 04:09 PM
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No voltage reading

I get the same click followed by humming sound at the unit whether the outside fuses are out or in. I can't get any voltage readings at the contactor.
Time to call a pro unless there is something else easy I can try.
 
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Old 09-01-08, 08:39 PM
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Ok, no voltage at contactors, then try to take a reading at the disconnect switch on the wall before and after the fuse.

if you get power before the fuse, and nothing after, then the fuse are blown.
 
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Old 09-01-08, 09:23 PM
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No voltage before or after fuses.
Voltage checks ok were the wire screws in on circuit breakers inside at the main panel.
Guessing I need an electrician.
 
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Old 09-01-08, 09:53 PM
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Have you done any work on the house or remodel?

Was the breaker tripped? Also, are you able to follow the wire from the panel to the outdoor to see any damage?
 
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Old 09-01-08, 10:20 PM
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The furnace/ac breaker never tripped.

I did replace some exterior lights today and tripped that breaker a few times. I was trying to complete that project while troubleshooting the a/c. The new lights don't work either, but I might not have grounded properly. The other lights off that circuit work fine.

Otherwise, no other projects lately.

No, I can't follow the wire from the panel to the outdoor fuses.
 
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Old 09-01-08, 10:56 PM
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Then it may be time to call the electrician to come out to see why or where you are losing power at.
 
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Old 09-02-08, 07:14 AM
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Couldn't this be a bad breaker?
 
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Old 09-02-08, 07:17 AM
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Originally Posted by mmead View Post
Couldn't this be a bad breaker?
I don't think so.. He said he check for power at the the screws where the wire goes to at the breaker, and he got a reading.
 
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Old 09-02-08, 07:48 AM
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In the past month we have had a similar situation on the forum. It was corrected by looking for the following.
You say the a/c is old. Is the home old as well?
If you have no voltage at the top of the disconnect and you do have it at the outgoing terminals of the breaker, then you have an open circuit in between the two. I would would start at the service to the outside disconnect and trace the feed back toward the breaker panel. I can't imagine that size wire just opening up.
As the guy who posted less than a month back, he found a switch box outside of the house in the alley that was between the panel and outside disconnect. LOL
 
 

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