A/C system noise/whistling - lets sum all the information pals

Hello everyone.
I saw a few posts about A/C system noise here and decided to write a topic with all the information I have collected until now. Some of you guys here have a mechanical background and maybe could help me and other guys here. Hope other people that suffering from the same problem can throw the information about this info to this topic so we will maybe have some database to find a solution.

The background: my car is a honda civic hatchback 2018 manual transmission. bought it just this July and even in the first drive home from the dealer I already noticed some strange whining sound (the first drive was without music so every small noise was noticeable).

The first dealer visit: after 1000 KM I went to the dealer. We found that the noise appears on 2100 +- and 2750+- revs every time. It is not connected in any way to the throttle pedal. after a few minutes, my dealer decided to replace the compressor since he "heard the noise coming from it. We replaced the compressor but, nothing changed.

The second dealer visit: after coming back to the dealer on the next day we tried to replace the A/C compressor pulley, then another one and nothing really changed. Same revs, same noise, same problem.

Trying other cars: after so many parts my dealer started to run out of ideas and we just tried another car in the service. It was the same hatchback from 2016 but with the CVT transmission. Surprisingly (or not) we heard the same noise exactly on the same revs.

Contacting Honda outside my country: I tried to find some solution before contacting the main office in my country and got this piece of info from Honda agent:

"...It sounds like the 2SV noisy A/C issue to me but this is under investigation so we would not advise anything from here until that has finished..."

Now when I know this is not only my car I feel a little awkward. On one hand, it supposed to be "normal" on another hand this noise sometimes drives me so crazy that I start to find any radio station just to cover this whistle noise while driving. My next step is just to wait for another answer from abroad and maybe get some compensation from my local Honda company.

Maybe some of you guys can transform this information to some advice, or just can explain what is 2SV noise. If not, thanks for reading and sorry for my English, I don't live in an English speaking country .

I have the same issue with my 2018 Civic Sport Hatchback, manual trans. The Rev range is much tighter on mine where the noise is audible- maybe 2750 +/-100 rpm. I'll investigate more today to see if it goes away with the AC off.

The noise is not as loud now, with cooler weather and short drives around town. It was barely noticeable today. It seems to be loudest with hot ambient temperature and hot engine (during longer drives).

fwiw mine makes the same exact noise that you guys are talking about. My guess is they all do, some of us just have keener dog whistle ears

My wife and I both have HB’s. Mine makes the whistle coming from the AC, more prominently under acceleration. Goes away immediately after I turn the AC off. Is annoying when trying to enjoy a quiet drive to work. Can’t hear it with music on.

My wife’s makes no noise.

I’m going to point it out at the dealership when I take it in for them to review a door rattle and what I assume is loose weather sealing in the drivers window because I can hear air coming in like the windows cracked anytime I’m going above 50.

I actually have been complaining to my dealership about this on my 17' Sedan. I'll be checking about revving around those RPM. I've taken mine in twice already and the first time was that Honda was saying my AC was overcharging so they recharged it.

I have the exact same issue in my 2017 EX-T CVT. The whistling isn't there if AC is turned off.

I also have the same issue on my 18 HB. I've tried to pay closer attention to it over the past week. Here's what I've noticed:

• Only occurs with AC on (tested by turning AC to Off in climate settings)
• Occurs between 1,000 and 2,000 RPMs, most often between 1,500 and 2,000 RPMs
• Occurs more noticeably under acceleration *but* lower speeds (< 25MPH), like going up and through a parking garage

I'm only at 3,000 miles on my hatch, so will likely wait until first oil change and bring it up to the dealer then.

steviiee said:

I actually have been complaining to my dealership about this on my 17' Sedan. I'll be checking about revving around those RPM. I've taken mine in twice already and the first time was that Honda was saying my AC was overcharging so they recharged it.

Click to expand...

And the whistle is gone?

Can you explain a little more what they did to you? just changed the amount of gas inside?

Bumping this thread in dire hopes there's an answer here from one of you!?

Just picked up my new 2018 and this is driving me nuts. Had a slight headache already and this made it worse. Such a annoying high-pitched whine. Not happy & concerned that I've yet to hear of a cause and solution.

Per my other post it sounds VERY much like on older car stereos when a crappy AUX input cable picks up ignition interference and it comes through the stereo....remember those cassette tape adapters for portable CD walkmans? Yeah, dating myself, but this sounds very similar. I'd swear it STILL is coming from the speakers except turning the stereo off makes no diff, but the AC/fans off does stop it!

I've heard bad dash fans. It's not that. This is clearly rpm related as you all said too. I'll be forwarding this thread and a few others to my dealer rep for review. Please update us.

You're right! It does sound like the old radio interference. But it is definitely the AC. Now that the weather has turned cold here in Ohio, it's not making the noise now.

Interesting, I'll have to take a closer look at this. My wife's 6MT '18 sport hatch makes an odd noise accelerating at around 3000 rpm or so, and another noise when decelerating in gear, not entirely dissimilar from the noise the parking brake makes when it actuates. It drives normally, just with the noise.

mine does the same thing... 18 si sedan. turn off the ac and the noise stops tho

Update: Took it in, and was told the same as this thread. It's a manufacturing defect with the AC compressor across all cars and there's no fix for it. They could put in a new compressor but "it'll make the same noise because it's the same part/design".

Was told it could take several weeks to get a Honda Tech in to look at it.

Have any of you had any luck in getting this fixed in any way, shape, or form?

Or has Honda done anything to make it right? This noise bothers me every time I drive it, and I can't go without AC in FL.

My A/C makes a chirping or fluttering sound and it goes away if I turn the A/C off but keep the fan running. Dealership heard it and wants to replace the blower motor. I questioned that since the sound is only there when the A/C is on.