Central AC fan runs, cool air takes forever to start


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Old 06-27-20, 11:18 AM
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Central AC fan runs, cool air takes forever to start

Hello all,
I could really use some help diagnosing a central ac issue. When my central ac unit turns on after being off for a long period of time, it works great, plenty of cool air. However, after it switches off at desired temp, and then back on after an an hour or two, the fan will run, but no actual cool air.

Here are some symptoms:
  • seems to be worse during the hot, middle of the day
  • its almost like condenser "struggles" to turn on. At night, you can see lights dim as it tries, fails, meanwhile blowing lukewarm air, tries again (lights dim for a second), repeating until cool air actually starts again.
  • cool air when it finally comes is cold and cools house well
  • Unless ac has been off for many hours, during middle of day, it will take almost an hour before cool air starts
  • at night, less of an issue, problem still happens but cool air starts up sooner.
  • the longer I have it off, the more of a chance it will start right up with cool air soon. only seems to happen after it was running for a while, switches off, and then turns back on with house slightly warmer.
Any help would be so much appreciated!!!
Thad from RI
 
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Old 06-27-20, 11:25 AM
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You need to focus on the outside condenser.

It maybe something as simple as weak capacitor.
When it starts does the fan run ?
Does the compressor start or is it cycling ?
You can hear this if you listen. If you can't you'll need to have the condenser serviced.
 
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Old 06-27-20, 11:30 AM
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Hi PJmax,
thank you for your reply.

When it starts, the fan always starts up and runs the whole time, no issues. Only the accompanying cool air is the issue.

I'm not sure what you mean when you say "does the compressor start or is it cycling"
 
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Old 06-27-20, 11:48 AM
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The condenser is two parts..... a compressor and a fan. The fan is in the top of the unit and is very easy to see. The compressor is down inside and compresses the refrigerant and sends it inside under pressure. If the compressor doesn't start there will be no cooling.

The fan makes a whooshing sound and the compressor rumbles when it runs. Also.... when the compressor is actually running..... the larger copper pipe(insulated) behind the unit needs to get ice cold. If it's not....the compressor is not running.
 
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Old 06-27-20, 12:40 PM
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Thank you so much for the info!

Yes both the blower fan under near the furnace in the basement and the fan on the top of the outdoor unit run anytime the unit is on. No issues there.

Thank you for the info about the compressor, I will listen for the rumble.

I will check on the larger insulated copper pipe. I'm guessing when the unit is working correctly, it will be cold. Its not that I don't get cold air ever. It's that when the unit turns on after only being off for a short while, the cold air takes a long time to be produced.

Thanks again
 
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Old 06-27-20, 09:17 PM
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My guess would be you may have a stressed capacitor. It could be causing the compressor to have a problem starting. You need to let us know if this is something you will be trying to repair yourself.
 
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Old 06-28-20, 12:45 PM
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Hi there

Thank you I plan on following the steps in this video exactly:

https://m.youtube.com/watch?v=9ZGfvC-PMWU

let me know if you have additional advice!
thanks!!
 
 

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