Hissing noise from AC


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Old 08-02-14, 05:22 PM
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Hissing noise from AC

My home air conditioner started making a hissing noise and then could not get temp below 79F. It stopped hissing after I shut the AC off
After an hour I turned it back on again, house went from 82 to 79 in about 20 minutes. Then heard a small 'pop' sound when I was outside and it started hissing again. Any ideas?? The unit is just shy of 6 years old.
 
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Old 08-02-14, 06:10 PM
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Does the outdoor fan continue to run when you hear this internal bypass?
 
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Old 08-02-14, 06:15 PM
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Hissing when the compressor is running sounds like a refrigerant leak.
 
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Old 08-02-14, 06:16 PM
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Can't really tell, the unit is on the roof. Will turn it back on and listen.
 
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Old 08-02-14, 06:22 PM
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AC on for 5 minutes now. Cold air is coming in through vents and it does sound like the fan is on, although it just sounds mostly like motor noise to me.
 
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Old 08-02-14, 06:26 PM
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After 10 minutes, still cold air blowing, no hissing noise, but there is a high pitched vibration-type noise coming from the unit. Almost list something that is spinning isn't balanced.
 
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Old 08-02-14, 06:40 PM
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After 20 minutes, the unit sounded like it was just humming, didn't have any sort of spinning/fan-like sound to it. The humming started to get louder for about a minute, then the 'pop' noise followed by the hissing sound. I've turned it off. Any ideas? Hopefully inexpensive ideas??
 
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Old 08-02-14, 07:22 PM
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May just need a servicing. Unit could be really dirty causing high head pressure. Its hard to diagnose it though without hearing it or really seeing what's going on.
 
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Old 08-02-14, 07:33 PM
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Sounds like bad bearings in the fan motor cause it to stop and the compressor is going into internal bypass.

It is definitely time to call a pro if you cannot even get to the unit to see the fan.
 
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Old 08-04-14, 10:01 AM
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The HVAC guys came out today and told me it was the fan motor, as you had said. Thanks for your help on this. $580 is the bill, don't know if this is a lot for such a small motor, but at least I will get some relief from the 105 degree temps we've been having!
 
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Old 08-04-14, 10:38 AM
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My Callahan/Roach flat rate price book shows $577 for a universal 1/4 HP motor installed price including tax.
 
 

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