Overrated!
Bought this Haier 'quiet' ac after buying a LG 5000 btu ac but I thought the LG was too noisy. Comparing both Haier and LG on low fan speed Haier ia indeed quieter, but not by a lot. Using a sound meter on my samsung phone the difference between the two are merely 4-5 db (haier is about 56 57 while LG is about 61 62)
But I do have to mention that the noise from haier is less disturbing than LGs. It may be because haier's is more of a wind noise while LG ia more a mix of wind and compressor noise??
But the problem is the air flow of the haier is so much weaker than the LG. When I put my forearm over the vent the LG low fan speed feels the same as Haier high fan spend; even though the spec says otherwise.
Another thing is the coolness. Turning both unit to the coolest setting and LG blows much cooler air than haier!
So, in my opinion this haier serenity ac is way overrated and not worth the premium price. I got the LG for $127.

I bought this 100% for the reviews on being quiet. I have a 400$ unit that does 12,000 BTU and a 90$ unit from walmart that does 4,000. So i have had my fair share of "cheap" units, so this purchase was to finally compare this unit with the cheaper units.
First this is definitely quiet.
Secondly, i think this truly is a 6K BTU unit. On high very cold.

Con,
which is the fan doesn't go really high. Now this is mainly because the lower the fan the quieter the unit, and they need to keep the title of "worlds quietest AC unit" so they didn't make the fan too high. However, even with that said, i will definitely purchase another! I do like my room to feel breezy so take this with a grain of salt.

Bought this in the winter! The previous window A/C that came with the room I rent was good at cooling but horrifically LOUD!
The sound when the bearing are out on a fan. Couldn't talk on the phone, sleep, or even watch TV with it on.

Today's the first 94 degree day so had a chance to run it. In quiet mode it's spooky quiet. But that speed was too slow to quickly cool the large bedroom. High speed is louder, a little distracting, but...I did fall asleep with it on high. Medium speed is perfect.
It did start that horrible compressor undulating vibration sounds. Remedied that by unfastening the front cover and then just lightly placing it back in position without snapping it in fully. Now....it's very quiet.
Update 8/6/2017: Definitely had a chance to test this unit out with some very hot days. I find that it takes a good 2 hours to cool down a 90 degree room at 300 sq. ft and 9 foot ceilings. I put it on Auto mode and energy saver. About the 3rd hour the fan slows to medium and then about 30 minutes later down to slow. Slow fan, and super quiet, is the norm from there on. Very quiet and cycles on and off as it should. My best advice, if you don't want to wait for the 2 hour cool down is to raise the temp setting while away, then lower it upon return. This will cut cool down time by about 60%.

While I do wish that the package had "this side up!" written on it, as FedEx delivered it on its side, I simply let it sit correctly for two days (to be completely safe, although the instructions say a few hours is enough), and started it up without any issues. It took a little bit of work to get rid of all of the vibrations, but, that isn't the air conditioners fault. Lucky for me, another reviewer here mentioned an idea, which helped me out a bit. I ended up taking their advice and wedging some paper in the air filter and I also wedged some paper between the metal guard that holds the top sash in place and the sash. To really crank the sash down on top of the unit, I used security locks that you thumb screw into the window frame while pressing down the window sash fairly firmly down onto the unit - this seemed to help with vibration as well when the compressor came on.

I will say that the fan on quiet is darn quiet. I use this in an office with 2 running PCs and 3 running laptops, so I already have some fans going at times, and I cannot even hear this over them. When the AC compressor turns on, there is a hum, but not very annoying or loud, especially when compared to a previous unit that I had.

I would definitely recommend this unit to anyone looking for a quiet unit. Do remember that it doesn't run silent, but, with a little extra work you can reduce additional vibration as well and make it as quiet as possible.

First of all, I think you need to know that I live in Southern California, so my demands are year round. Having said that, you will understand the date of my review is appropriate, but also more applicable than you might expect. I have gone around the bend trying to find a window AC for my study. I've been to Home Depot and Lowes on several occasions and settled for the usual Frigidaire, and LG units. They failed, got loud and eventually within a year wore out. My study is upstairs at the warmest corner of the house, which does not have air conditioning whatsoever. This means that this room needs a heat pump working the whole day as heat rises and collects here. I, like you had to read tons of reviews from people that proved to be no help.

I finally came to this air conditioner and tried to compare three units, this one, the Frigidaire 6,000 BTU 115V Window-Mounted Low Profile Air Conditioner with Full-Function Remote Control, then the same conditioner made by Crosley by Frigidaire Low Profile 6000 BTU Window Air Conditioner CLP06EHQ1. The last 2 were too big- wide for my window and appeared to be just as loud as my LG unit I just gave back.
There is a lot of chatter about the Haier (Hi-er) brand, and the serenity line. Most of the reviews trash the dB levels, but they would be wrong. I measured the dB with my phone app, and the LG had significantly louder sound, almost double.

But the killer is that the Haier is not only quieter, but conditions the air with a combination of fan modes, all of which are quiet. From room ambient sound levels at 44dB, the fan comes on at 55dB, and the motor kicks in at 63 dB. Remember the beginning levels are already at 44dB! But these are levels standing inches away from the unit. When you come away 3 feet, the sound for the fan goes down to 46dB, when the motor kicks on the level goes down to 55dB. When I speak into the phone at conversational level it is at 71dB. Therefore, you can read, talk on the pone, or watch the TV without even knowing the airconditioner is on!!!!!

My next step is to get some neoprene foam rated at 30+- density to cushion the vibration and deaden the sound even more.

Note: I had to tuck foam pieces against the vent hinges to keep them from vibrating, and a couple strips inside the front cover to press against the filter to keep that from vibrating as well. You can't see them and they dont interfere with the function.

Lastly; the air conditioner is very accurate. See the pictures and you will see when the unit turns on- it is only off by +- 2 degrees. This is important because if the temp gauge is off more than that- it will stay on for longer than necessary and turn on at higher temps. If the gauge is +- more the 4 degrees this means that it probably will not be efficient. This is really important because when the unit (compressor) works harder than it needs to, then it will wear out much faster, and never keep up with rising temperatures you want. You will get a noisy compressor and vibrating mounts inside the unit will begin to rattle.

The only complaint I might have is that the front comes out from the window mount about 6 inches. This is the front and is designed with sound deadening foam. This extra space is lined with foam and acts as an air basin from which the cool refrigerant coils can be positioned further away from the outside heat pump and sound. This is a very nice trade off all things considered. I don't need to worry about that extra space coming into the room anyway.

This is the best little air conditioner I have ever bought. The research paid off.