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  1. #1

    Hissing noise from AC unit

    My AC developed a hissing noise today. I was outside when I heard a 'pop' and then there was a hissing sound. It did not seem to be blowing any cold air after this point. I turned it off, and then back on again about 2 hours later. For the first 10 minutes there was cold air coming out of the vents. Then there was a squeaking noise from the AC unit that sounded like something might be out of balance. After 20 minutes the squeaking noise stopped and it didn't sound like the fan was running (the AC is on the roof, so I couldn't tell for sure). Furthermore, the unit was only making a humming sound that grew louder for about a minute. After this, there was a 'pop' sound and then the hissing began. There is no hissing when the unit is off. Any ideas? The unit is just under 6 years old. Could it be the compressor?

  2. #2
    Join Date
    Jul 2011
    Location
    Dallas, TX.
    Posts
    183
    Turn the t stat to off fan on. Then call a reliable company out. Not the last company that came out. Good luck...

    Edit^^^
    Last edited by CEAS-AC-TECH; 08-03-2014 at 12:11 AM.

  3. #3
    Join Date
    Jul 2005
    Posts
    5,576
    Quote Originally Posted by baconman View Post
    My AC developed a hissing noise today. I was outside when I heard a 'pop' and then there was a hissing sound. It did not seem to be blowing any cold air after this point. I turned it off, and then back on again about 2 hours later. For the first 10 minutes there was cold air coming out of the vents. Then there was a squeaking noise from the AC unit that sounded like something might be out of balance. After 20 minutes the squeaking noise stopped and it didn't sound like the fan was running (the AC is on the roof, so I couldn't tell for sure). Furthermore, the unit was only making a humming sound that grew louder for about a minute. After this, there was a 'pop' sound and then the hissing began. There is no hissing when the unit is off. Any ideas? The unit is just under 6 years old. Could it be the compressor?
    The fan is quitting for some reason, which is causing the compressor to go into bypass mode. The bypass mechanism is the reason for the pop and hissing sounds that you're hearing. This is not good for the compressor. Shut the unit down until it's fixed.

  4. #4
    Join Date
    Mar 2013
    Location
    Springville, NY
    Posts
    3,528
    this is nearly the exact same thing i told him on another forum...
    Political Correctness, the language of wussies.

  5. #5

    Thanks!

    Quote Originally Posted by hvacrmedic View Post
    The fan is quitting for some reason, which is causing the compressor to go into bypass mode. The bypass mechanism is the reason for the pop and hissing sounds that you're hearing. This is not good for the compressor. Shut the unit down until it's fixed.
    The HVAC guys came out today and said it was the fan motor, everything else looks to be in very good shape. $580 is the bill, not sure why they need two people to do this, motor is pretty small. Thanks for your comments.

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