Loud noise - losing my mind

[Britvegas]

Thank you, in advance for your willingness to help. I feel like I’m losing my mind. Please forgive me if I don’t know all of the proper verbiage.

About a month ago we had the furnace and coils in our attic replaced because of a leaking drip pan (and the unit was 23 years old). The condenser outside is two years old. Ever since the equipment in the attic was replaced we get this high pitched squeal in the house.

Here is the weird part: it only happens at night! Usually between the hours of 9pm and 9am. We can’t really hear it outside or up in the attic, but it’s VERY loud in the two bedrooms (first and second floor) that share a wall with the outside unit. I’m 99% sure it’s the lines vibrating in the wall. The a/c guy has come out twice but since it doesn’t make the noise during the day we can’t tell if the adjustments are helping or not. It’s so loud in our bedroom that it wakes me up from a dead sleep, even with earplugs.

Please help!

[NETWizz]

Does it should like very loud crickets and from the outside unit?

[Britvegas]

To be honest, it doesn’t really sound like anything except the whirl of the fan blades. Same as my other unit, right next to it.

[Britvegas]

Actually, it sounds a little bit like a quiet buzzz saw.

[firecontrol]

Start tracking the indoor and outdoor temperatures for a week. It might have something to do with inside or outside temperatures. Do you turn the temperature down in the house for nights?

Does the wall that the noise is coming from get a lot of sun in the afternoon?

Lines vibrating in the wall wouldn't/shouldn't produce a high pitched squeal, but a TXV in your air handler in the attic could under certain conditions that could resonate that sound down the lines in the wall. At least that's the only thing I can come up with by your description.

The more information and variables that you can document and provide to the tech the better chance you have of this getting resolved quickly.

[Britvegas]

I have been doing a bit of that. Our thermostats are on a schedule. They are set at 78 during the day and then go down to 76 at 6pm and 74 at 8pm. I did think it had something to do with that, so today I left it at 74 all day and the noise went away around 8:30am as per usual. The outside temperatures have been fluctuating between 90 and 105 for the last week. It’s a north facing wall, so no direct sunlight except between 3pm and 6pm.

I should also mention that the unit is cooling very well. I have an audio clip of the noise inside our bedroom at night, but am unsure how to post it.

My a/c guy came out again today (of course the unit was quiet) and put the condenser up on rubber footings. He said the next step if it it’s resolved is to put a braided wire on the line that goes into the wall? Worse come to worse, try and pinpoint the worst spot of vibration and cut a hole in the wall.

[NETWizz]

Upload it to filebin or even yourube and link it

[Britvegas]

apparently I need three more posted to post a link. Apologies

[Britvegas]

Two more to link

[Britvegas]

Link coming in next post. Thanks for your patience.

[Britvegas]

Just kidding. Apparently I need one more 🙄

[Britvegas]

Okay, here’s isn’t a video of me being outside and then walking in to the bedroom so you can hear the noise I’m dealing with. Honestly, it’s even louder than the video shows:

https://filebin.net/wt4p2shmc2fily9o

Thanks

[pacnw]

2 things.

First, hard to tell from that video, but is there ice/frost on those lines in the outdoor unit?

Second, that noise is similar to harmonic vibration through a return grill. It is also possible that, while you feel it is cooling correctly, it is NOT at the times this is happening.

Did the size of the indoor unit change, not just in measurement but in capacity. Was a proper start up done to check airflow?

[Britvegas]

Definitely no ice or frost at all. Also, I guess it could not be cooling properly, but the air seems to be coming out of the vents very cold and the cycles don’t seems to be any longer than usual.

Apparently the older/former unit was oversized for the condensing unit and the new coils/furnace is properly sized.

Not sure what you mean by “start up”. I did change the air filters today and one was a little off kilter. Could something that simple be the cause?

The main thing I can’t understand is why it only happens at night and never during the day.

[firecontrol]

To me, when you're by the outdoor unit, it sounds as if the compressor is being slugged with liquid. I realize this probably doesn't mean a thing to you, but if you tell that to the service tech it might help them to figure out what is going on. Show them the video. That noise is a rattling noise of the mechanical parts inside the compressor trying to compress liquid refrigerant, not gas like it's designed to do. THIS IS AN OPINION, not an onsite diagnosis.

Next time you talk to them ask three things: 1) Does the new indoor unit in the attic have a TXV? 2) If the indoor unit has a TXV, is the outdoor unit charged to the correct sub-cooling temperature? 3) What is the total external static pressure across the unit in the attic?

If I had to guess (and of course we all are) I'd say as you lower the temperature in the house at night, and the outside temperature outside lowers, the indoor coil is freezing up and allowing liquid to return to the compressor. Another guess is that when the noise starts, the air coming out of your registers is a lot less than normal.

[Britvegas]

Thank you so much for your input, I really appreciate it. I was actually really hopeful when I woke up this morning, as it didn’t make the noise all night. However, at 7am, when the unit clicked on, there it was. The outside temp was 87 degrees and the unit was set to 78 (the schedule kicks it from 74 to 78 at 2am.

I checked the outflow from the vents upstairs and it seems very strong and ice cold.

Here’s the kicker, when I was looking around outside, the little pipe that goes into the house connected to the condenser (refrigerant line?) is vibrating nearly too hard to even hold. When I moved it up and down (only a tiny bit of play) it definitely changed the sound. I think I’ve isolated inside along the wall where the noise is the loudest. It’s between the floors, right near the floor of the second story. At what point do I just have my HVAC guy cut a hole into the wall and see if it’s rubbing on the header?

[Britvegas]

Okay, we’re an hour later. 4 degrees warmer outside and zero noise. I checked and the little line is barely vibrating at all. What could cause it to vibrate so strong at one time and then hardly at all another? The most challenging part is that since it doesn’t make the noise when the HVAC tech is out here, it’s just a guessing game. I even tried to get it to make the noise by moving the little line but no luck.

[Bazooka Joe]

Thank you so much for your input, I really appreciate it. I was actually really hopeful when I woke up this morning, as it didn’t make the noise all night. However, at 7am, when the unit clicked on, there it was. The outside temp was 87 degrees and the unit was set to 78 (the schedule kicks it from 74 to 78 at 2am.

I checked the outflow from the vents upstairs and it seems very strong and ice cold.

Here’s the kicker, when I was looking around outside, the little pipe that goes into the house connected to the condenser (refrigerant line?) is vibrating nearly too hard to even hold. When I moved it up and down (only a tiny bit of play) it definitely changed the sound. I think I’ve isolated inside along the wall where the noise is the loudest. It’s between the floors, right near the floor of the second story. At what point do I just have my HVAC guy cut a hole into the wall and see if it’s rubbing on the header?

Take a video of the Liquid line vibrating, and any unusual noise to show the Installing Contractor. The Liquid line by the OD should be secured firmly to the insulated vapor line or however the lineset was run. Maybe having the liquid line better secured may stop the noise inside the house, also possibly by the ID coil or where it penetrates anywhere may need to be secured better. Take several clear photos of the liquid line OD and ID to post here to see if it's secured sufficiently.

[Britvegas]

I took this video this morning but not sure if it shows enough:
https://filebin.net/27beinc7wpg17yaf

[NETWizz]

When the contractor comes out please have the contractor give you he metrics. We want low and high side pressures and line-set temperatures please. Also need to know if there is a TXV.


This will help us get an idea of the unit is overcharged flooding back.