Outside unit turns on and off constantly.


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Old 04-08-13, 05:40 PM
J
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Outside unit turns on and off constantly.

I live in a two story Townhouse and have one AC unit outside and two thermostats, one on each floor. Recently, i have been having the following problem. If i turn the air on, the outside unit and inside blower come on with no problems. However, after a few minutes, the outside unit shuts off and then comes back on after about 30-60 seconds. This repeats every few minutes until the desired temp is reached inside. Inside, the air never stops blowing through the vents, even when the outside unit shuts off. There is a VERY brief pause, maybe half a second, then the air inside just keeps blowing. Same thing when the outside unit turns back on, there is a very brief pause inside, then the air keeps blowing.

I've had someone check my freon levels and they were fine and technically everything is working, in the sense that the place is being cooled down to the desired temperature. That said, i'm guessing it is not working efficiently with the outside unit constantly shutting on and off constantly. It also feels like the unit is running much longer than needed (which would make sense with the behavior of the outside unit).

Any insight into this? I'm particularly confused that the outdoor unit is shutting on/off but inside the air through the vents just keeps blowing. Eventually, both do shut off though when the desired temp is reached.
 
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Old 04-08-13, 07:57 PM
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You say you had someone check it and technically its working. Well if its doing what you said its not working right and you will probably end up burning out your compressor shortly. I hope you didn't actually pay that person any money for not being able to troubleshoot worth a dam. You need someone who is competent to see why the unit is short cycling. Could be anything from a loose connection, faulty pressure switch, bad thermostat etc. If its doing it constantly it shouldn't be too hard to isolate the problem.
 
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Old 04-08-13, 09:17 PM
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Welcome to the forms.

As the apprentice said that is something you want looked at pronto. AC compressors don't tolerate short cycling for very long.....especially turning off and then back on in 30 seconds.
 
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Old 04-08-13, 09:42 PM
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Actually, now it is acting differently. It still starts the same way - indoor/outdoor unit both come on, outdoor unit goes off after a few minutes (indoor stays on), outdoor comes on again after a minute. However, now after this cycle happens a few times, the outdoor unit goes off and never comes back on again. The indoor unit stays on though, air continues to blow through the vents, but obviously there is no more cooling. At that point, even if i turn the thermostat to off, the air will continue to blow inside indefinitely. The only way to turn it off is by going into the attic and turning the whole unit off. Does this help narrow it down at all?

As for the guy who checked Freon levels, it was a while ago and he was here for something completely different (i wasn't even aware of this problem at the time). He was just doing me a favor. And yes, i will get someone out soon, i just wanted to see if there was anything i can do myself first. Thanks for the feedback.

Oh and one other thing. I actually think this has been happening for years, not just recently. I say that because my place was being cooled just fine and since the indoor unit stayed on and air was blowing through the vents, i never noticed what the outdoor unit was doing until just recently. The only thing i noticed was that VERY brief pause on the indoor uni/vents when the the outdoor unit turned off and on. I shouldn't have ignored it but did because it was cooling ok.
 
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Old 04-08-13, 09:46 PM
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The compressor may be shutting down on thermal overload. You would have to have unit apart and voltmeter in hand to see what exactly is causing the shutdown.

My first thoughts are low on freon.
 
 

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