"Then 7 years later it started to fail this season" "Two of the coils would freeze up going all the way back to the thin wound wires." Sounds about right for a small window unit built to a price point. Time for a new one. They are rarely worth repairing (especially a small 120 V one) since there are no fittings installed to allow testing or filling the refrigerant.

mac I have an Econar GT heat pump in a second floor closet and had noise issues that were aweful. It turned out to be improper vibration dampening when the system was installed. The scroll compessors run between 50 and 60 cycles per second. The 3 stage fan in my 3 ton GT unit runs in the 1100 to 1800 RPM range (or 18 to 30 cycles per second). The guys who did the install laid the GT unit on the floor and put a rubber mat under the base. That mat became essentailly a vibration noise amplifier. I found that rubber can isolate very high frency vibs - not the lower frequnecies. The rubber is recommended at a minimum of 45 Hz - but it really doesn't work well until you get above 60. I know this is the case becuase my loop pumps in the basement run at 60 Hz and they are on rubber mats too - no vibration noise (there is acoustical noise from the impellar spinning - but that has to be dampened by other means). My solution was to jack up the unit - get if off the floor by 5 inches or so - and put vibration isolation mounts with springs on each of the 4 corners. These springs can dampen vibs down to a few Hz and up to 60Hz - they are much more effective then rubber in the frequnecy range of the unit. That fixed the problem. You can still hear the unit for the first 3 to 5 seconds after it first turns on - but once it is in steady state, it purrs. No louder than the hum of a refrigerator. My builder and HVAC contractor were stunned - appranetly they have this same issue in other houses they built with GT where people cannot sleep (but never told me that when they sold me the GT)! I think they owe me one. Your issue sounds similar to mine. Can you describe how the unit was installed - where it is, what is it resting on? What type of floor is it on - is it in a closet? Is the closet insulated? The site I used to but these products is www.acousticalsurfaces.com. Look under Vibration Mounts and then look under Housed Spring Mounts. The product is made by Mason Industries and needs to be chosen carefully based on your units corner weight. You need to determine if the noise you are hearing is acoustic noise or vibration noise. If it is acoustic noise - then you can use sound proofing insulation. If it is vibration noise - then you need dampeners. I used both - the walls of the room have insulation to dampen acoustic noise. The springs dampen vibration noise.

(Sorry for the confusion about which post to reply to - I'm not familiar with forum ettiquet and had started a new thread when I should have stuck with this one). The 24anb6 is a single stage. All conversations are centered around a 3 ton unit. The ducts are in the attic space. The original house was 1140q ft. The addition is about 488q ft. The original house (1950s) has a metal ducting trunkline system that runs in a dropped ceiling in the 12' long central hallway. The new ducting is in a jumble in the attic of the addition, with a big box thing (a baffle?) and 4.5" ducts curling around everywhere - even back to the front rooms of the original house. Apparently code has changed and new 'jumper' vents needed to be installed in all the rooms? Before that ceiling was closed up, I got a glimpse up there and noticed that it looked like and orgy of Robby the Robots - probably not the most efficient thing ever. If it's true that with the ductwork currently installed would not support a more efficient unit in the future without ripping out walls, I think this makes an even stronger case for upgrading the equipment now. (I work at home and I plan on living at this house a long, long time.). I was told when to pick out plumbing fixtures, hardware, lighting, etc...I guess expected to be told when to decide on the other choices involved. If the GC had asked, I could be looking at paying 10 or 11K for exactly what I want - a 2-stage, high-efficiency, quiet unit. Instead I'm having to choose between paying nearly 9k for stuff I don't want or - it seems from this email - paying twice for the install and associated repairs in addition to the upgrade. I'm going to push for exactly what I want. The GC is working up estimates for the Carrier Infinity 17, 19, and 21 SEER units. I have no problem paying the difference in the cost of the equipment, or even the cost the have the install done 'right', which I assume means moving the trunkline up to the attic and having a single trunkline.* I'm sure things will get sticky when we start discussing who pays for what. It would be so helpful to be able to get objective estimates from a neutral party on what the original install should have cost and what the install that I'm requesting will cost. Is that ever done? I'll post any progress as it happens. Thank so much for your feedback. It has so helpful in getting clarity on this situation! ************ *The email I received this morning regarding my request to move forward with the estimates for the 17, 19 and 21 seer units: "The 17,19,21 Seer units besides being even more expensive will likely require more duct replacement, more sheetrock removal, etc. as this will snowball the work; time frame would increase accordingly. " and "Regarding the duct work replacement, it should be noted that the metal ducting trunkline system & some ducting that pre-existed in your home is still in place & that airflow supply system may need to be upsized as well, as the Seer rating increases, expanding the scope of other sheetrock & installation repairs as well." It would seem that he really doesn't want me to upgrade...From what I can gather the difference in cost of the equipment between the builder-grade Comfort series and the Infinity series is about $1,500 - about 1% of the total project cost.

Thanks for the suggestions! I downloaded a trial verison of the DecibelX app (cool app!) and the readings actually came out pretty favourable relative to the specs. From about 1 metre, I was getting readings closer to 65 dB. I also just asked the technician (who's on site right now) and he said that the AC sounds normal. From what I've gathered, the unit is operating within spec and I was just expecting too much of the unit. I'm guessing that I notice the noise more on this unit because it reverberates between the two houses (where as the old unit was in a more open space). I also probably notice it more because I'm listening for it :P @fsq4cw, I wasn't trying to imply that the HVAC company should have to replace the unit at their expense (unless it was defective). I'm a more reasonable person than that haha! My only disappointment is that different sound levels weren't mentioned by the sales rep when he recommended the specific model (i.e. he said that only the efficiency improves as you move up the model line). I place part of the blame on myself for not researching the product line; however, I was given less than a day to make a decision (at a time that I was extremely busy) because Carrier promotions were ending. But regardless, if I'm actually getting 65 dB then my unit might already be operating at a spec that is better than the rating of some of their higher-end models. I'm not a typical client driven by price (and my sales rep was aware of that). I initiated a $500 upgrade to the Navien, the addition of a $400 humidifier, and the addition of duct cleaning. I just want reliable equipment from an HVAC company that will stand behind the products they sell, and I'm willing to pay extra for both :-) For my next steps, I'll ask the sales rep about the possibility of adding a sound blanket to the condenser to help reduce the noise a bit (which I'd pay for, since the unit is operating within spec). Thanks!