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Home A/C Periodically Blows Warm Air - Then Blows Cold After 30 Minute Restart

Home A/C Periodically Blows Warm Air - Then Blows Cold After 30 Minute Restart


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Old 06-23-16, 09:20 AM
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Home A/C Periodically Blows Warm Air - Then Blows Cold After 30 Minute Restart

This is an ongoing problem, which I've not been able to solve. By the time my A/C repair tech makes it out, the A/C is always working again. I'll describe what happens (this happens at least once every week now in the heat of the summer, it happens less often in the cooler times of year, I live in South Florida)

The A/C will be blowing cold air just fine, then all of a sudden it starts blowing warm air. What I haven't determined yet, is if it starts blowing warm air while it's running, or if it fails when it has been idol and starts up again due to temp increase.

When I notice that it is blowing warm air, I have verified that both the Handler and outdoor Condensing unit and fan are all up and running.

So far, the only solution to my problem is I go to the thermostat and shut off the system for 30 minutes or so. After 30 minutes or so, I go back to the thermostat and turn the system back on. After doing so, like clock-work, voila, the A/C blows cold again.

I really hope someone out there has the answer to this, because it is a constant nuisance, especially when it is 95 degrees outside. It takes about an hour for the temp of the house to rise by 10 degrees when this happens.

Based on my own research, it sounds like the Compressor could be the culprit. However, if so, what is causing it to continuously stop/start working - seems strange.

This A/C system is roughly 3 years old.

Any help would be appreciated - Thanks!
 
  #2  
Old 06-23-16, 11:00 AM
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Welcome to the forums.

You need to determine if the compressor is running when the condensor fan is. It's not always easy to hear over the roar of the fan. You could check by feeling the larger insulated copper line to see if it's cold.
 
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Old 06-23-16, 01:28 PM
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Thanks for the info, I will definitely check the compressor the next time it's blowing warm air. Now, let's say I determine the compressor is not running during the failure. That means something is causing it to shut down intermittently. Does that typically just mean the compressor is faulty and needs to be replaced? Or, could it mean something else is causing the compressor to fail?
 
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Old 06-23-16, 01:55 PM
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Doesn't mean the compressor is bad, it might be the low pressure switch is opening.
 
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Old 06-23-16, 01:59 PM
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Thanks, can you tell me why the low pressure switch would open?
 
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Old 06-23-16, 02:12 PM
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Could be low refrigerant, or even a bad switch.
 
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Old 06-23-16, 03:03 PM
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Ditto on what crabjoe said. Do you have a voltmeter?
 
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Old 06-23-16, 09:18 PM
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Fan motor going south and not able to remove enough heat leading to over temp protection to kick in for compressor?
 
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Old 06-24-16, 08:45 AM
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No - but I can get one very easily.
 
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Old 06-24-16, 08:48 AM
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Over temp protection sounds logical. Is there any way to determine for sure if that is what is happening? Or do I just have to replace the Fan Motor and hope?
 
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Old 06-24-16, 10:23 AM
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Have you checked the larger pipe to see if it's cold when it's blowing warm air?
 
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Old 06-24-16, 04:28 PM
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It is not a refrigerant/low pressure issue as that opens the contactor and the compressor AND the fan both don't run. You told us the fan was running.

It could be a run capacitor issue. It could be over heating if the fan isn't running up to speed.
 
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Old 06-24-16, 08:01 PM
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Run capacitor is an easy one to test (just did one myself w/ no prior experience). Seems like if it were run cap, it wouldn't provide enough juice to even start up the fan, though? I suppose there are different failure scenarios that could cause its RPMs to drop even after it somehow got spun up. In my case, there wasn't enough juice to get it spinning -- I could start it manually, but it then wouldn't spin fast enough to remove enough heat and everything shut off after 10-15 minutes and I'd just get warm air. Had to wait half an hour or so before I could even start the fan manually again.

Maybe one way to rule out the motor would be to use water to extract the heat? I've read of people doing this with a garden hose...
 
 

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