Air Conditioner noise - Tried everything

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  #1  
Old 03-21-04, 08:24 AM
DIY-Simpleton
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Air Conditioner noise - Tried everything

Hello, I have recently purchased a condo in Tampa, FL and discovered a quite annoying problem with my AC system. Whenever the AC condensor kicks on a high pitched buzzing noise occurs. I initially thought the problem was coming directly from the condensor unit outside, which is a 2 ton side air intake model. The original unit from 87' was replaced with a new unit and the noise still continued when the condensor kicks on. The AC repairman was also uncertain where this noise was coming from and inspected the attic. Still uncertain, I also had the original air handler replaced with a new janitrol unit (electric heat). Also I had a digital thermostat put in. Still the loud buzzing occurs. The noise sounds like it's coming from somewhere in the attic. It only last for a second maybe two but is loud enough to wake me up during the night when the AC comes on. The circuit breaker also have been replaced inside at the main box and in the outside box for the condensor. When the ac unit runs in the "ON" position the condensor still makes the noise. This has been a rather fustrating experience and I have run out of options. The other condominium units with the same AC units don't make this noise. Please let me know if anyone has any ideas or have incountered a similar problem. Thank you.
 
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Old 03-21-04, 08:49 AM
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Do I have this right. The AC makes noise just when it comes on?
The outdoor condensor unit is new. The indoor blower unit was replaced and is new . So what is left the line set ????

Do you get this noise when you go to just fan on no heat or AC?

Its not in any of the registers that resonates when the whole unit turns on .

Is there rubber pads under the condensor unit ?

ED
 
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Old 03-21-04, 09:15 AM
DIY-Simpleton
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Hi Ed, the AC makes the buzzing noise when the AC condensor kicks on. If I have the AC turned to off and the fan set to "ON" the buzzing noise doesn't occur when the fan starts. If you are standing next to the outdoor condensor when someone turns down the thermostat the buzzing noise isn't heard at all outside, just the normal sound of the condensor coming on but is heard by the person turning on the AC. The noise is only heard inside the condo. I am not sure what the line set is or registers? I am left thinking the problem lies somewhere inbetween the air handler and the outdoor condensor, which is a span of only 25ft. Thanks for you help Ed.
Nate
 
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Old 03-21-04, 12:09 PM
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That 25ft from unit to blower is the line set You will have a small one and a large one the big one will have like a black foam on it. When you hear the noise feel the lines see if it can be in them.
Then we have sometimes the relay in the outdoor unit will buzz when it pulls in. You didnt say how old the condensor was but that relay can buzz loud some times. With bad points it cant pull all the way in. Might look at that also . The only other thing that make a buzzing is the transformers on some units. that would be in the inside unit. Dont see how start and stop would do it, but could. Here you have to feel the transformer if you dont hear it ED
 
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Old 03-21-04, 01:46 PM
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I think he said...

The sound is only audible in the house.
I think what you might have is harmonic distortion. This happens sometimes, it might be because of the metering device also. if you dont have a TXV, do it, it controls better and is easier for the mechanic to charge (sight glass).
The other is, you may need to contact technical assistance from the manufacturer to get a muffler, or some type of baffle plate installed in the line set. Over the counter mufflers are available, ...One other thing is, if the mechanic didn't deburr the copper piping, you might have cavitation singing in the pipe like in the typical shower from plumbing pipes.

 
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Old 03-21-04, 04:00 PM
DIY-Simpleton
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HVAC01543

HVAC01543, do you work at discount autoparts? I don't appreciate your bogus post. Be nice.
 
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Old 03-21-04, 04:05 PM
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Was thinking about that also

Could be but he had the noise inside with the old blower coil unit. Now he has a all new Janitrol blower coil unit and the same noise. It should have a new metering device on it. 2 ton AC dont think a txv on it. Didnt say what new outdoor unit is. Next is the new condenser a match Janitrol for the new Janitrol blower coil unit. Are the lines the right size for this new set up?

Its times like this I wish we still had the old RFC set up .

No there are mufflers used on the AC most heat pumps will have them on. hvac01453 dont work for a auto store.

ED
 

Last edited by Ed Imeduc; 03-22-04 at 06:29 AM.
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Old 03-21-04, 06:28 PM
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HVAC is right on his posts not bogus. I was thinking either it has a piston metering device that can make these noises. I would change out for a TXV or it could be overcharged or the linesets could be undersized.
 
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Old 03-22-04, 06:26 AM
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Just .02 cents more

You didnt say if this was a heatpump or not. Know they use them a lot over there in tampa . Could it be the bypass set up there in the indoor coil for the heat pump. Most heat pumps 4 way valves go to heat when off or fail . So each time you turn the AC on this valve works and would also make the inside change over work could this be making the noise?

ED
 
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Old 03-22-04, 04:11 PM
DIY-Simpleton
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sorry

thanks to the above posters for your replies. I have never heard of a "TVX" and don't know where it's located. Could anyone fill me in. The outside condesor unit is less than a year old. I don't have a heat pump system. This afternoon I crawled up in the attic to take a look around and didn't see anything significant. Another piece of information is if you turn down the air so the compressor kicks in and then turn it back up so it turns off, the next time you turn the air back down the buzzing noise last more like 10 seconds instead of 2. I am assuming this is due to the wiring to the condensor and perhaps a cutoff timer for the condensor??
Any suggestions? Also, the noise is very strange becuase it doesn't seem to come directly from the condensor or the air handler. Thanks
Nate
 
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Old 03-22-04, 04:21 PM
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The TXV is an expansion valve its up there at the blower coil in the attic. Let just say its a tstat that keeps the right temp in the coil there . It like lets the freon in the coil when it needs it . Would you say that this is the same noise that the other coil made ? Can you put your ear and hand right there on the small line there at the blower and ha e some one turn it on ED
 
  #12  
Old 03-22-04, 06:00 PM
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Unknown sound

The line set may have a restriction. The gases are balancing on the off cycle. What is the condensing unit model# and outside dimentions of the line set?
Must be the line set...you replaced everything else!
 
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Old 03-22-04, 06:04 PM
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Simpleton

My posts are real, if they sound bogus it's because of your limited understanding in my field, I won't pretend to know yours!
 
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Old 03-22-04, 06:20 PM
DIY-Simpleton
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Problem Solved

My apologies HVAC, I am just an average consumer and don't know the technical terms in the AC field.
I found out the problem was coming from a metal conduit in the attic. The high voltage wires running to the outside breaker box for the condensor were run through a metal couduit that wasn't properly secured to the ceiling rafters. Thus when the power was turned on the metal pipe vibrated against the ceiling. I wedged some insulation around the pipe and it no longer makes that buzzing noise. So if anyone else comes across a similar problem you will know why.
Thanks for all your responses, especially ED and HVAC. This forum is a great service for us regular people like myself.
 
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