KenRLX

Since new, the AC had a constant pitch moan/low frequency whistle. The noise was not a rattle/clatter, it did not change with engine RPM or speed, but would get louder a bit with higher RPM. Driving at 20-45mph on a smooth road, it was the loudest single sound in the car (xcept the radio or the wife....)


It struck me that the one note tone could be a resonance caused by the AC fluid going through the piping, so I got out an old style listening probe like used on valve tappets, and found when listening to the low pressure AC tube, the same noise was there. It was on the HP side too, but not as strong. I also noticed that the metal AC tubing though tied down, didn't have much 'damping' on it so I was wondering if it was a 'tubular bell' kind of resonance.


So off to the auto store to get a few feet of 5/16 and 5/8 heater hose... slit some sections, clamped or tie wrapped them on several of the straight parts of the metal AC tubing that were accessible between the front of the car and the firewall.. and noted right away that when tapping the tubes they sounded much more damped.


Before adding the hose sections I took the car for a careful listen.. then same day. about an hour later,, same roads/condition.. moan was GONE.


No bolts loosened, no factory parts altered in this mod.. just adding some sections of slit hose and tie wrap/loosely clamp to dampen the vibrating metal AC tubes.


For those shade tree mechanics with this problem, it might be worth a try. I doubt this would affect a rattle/rumble sound or one that changes pitch with engine or road speed.


Now,,, if Acura can figure out that rattle that is even more obnoxious since the noise level is down.


And I'll update if the noise returns after a few more days/weeks.

EE4Life

Known issue. See TSB 13-026 - A/C Moans From the Engine Area in the TSB sticky thread.

https://acurazine.com/forums/3g-rlx-2013-412/rlx-tsbs-905784/

KenRLX

Yep a known issue, with some users saying that the moan exists after the TSB fix.. I'll track with my car, but with luck have knocked down the moan without breaking AC connections or taking trips to the somewhat distant dealer.

holografique

OMG...I'm NOT CRAZY! Thank you KenRLX. You have no idea how much this continues to bug the living daylights out of me.

And I am one of those who reported that the issue was NOT resolved after the TSB fix was performed on my car.

I'm going to review your fix here, but may contact you offline if I need more details to do the same on mine and see if it works.

Thank you again!

KenRLX

As a follow up, after some days of driving, I can still say there is NO sign of that AC moan. Before the fix, the sound would be annoying and would abruptly stop if the AC were turned off. At least for the problem that is on this RLX, all is good. The noise was there for months, then the day I put the hose segment dampers on the metal AC tubing, it was gone.
The 5/8 heater and 5/16 fuel lines used to wrap/dampen the metal AC tubing are rated for under hood temps, but the standard nylon tie wraps are not. So I bought some ETFE tie wraps rated to way higher than the under hood can get. Also, I started with a couple of hose clamps and tie wraps, but suitable tie wraps do just as good, are neater and easier to install.
On my next trip to the dealer, I'll show service what I did.
And again, yes, there is a TSB, but I am glad to get it resolved, find root cause, and not have to break open and recharge the AC lines.

holografique

Excellent work and report Ken. Thank you soo much. If you don't mind, can you provide a simple BOM (bill of materials) list for the components you purchased and recommend, and just a couple of pictures showing each area where you placed the additional dampening?

I should have time this week in the early evening to do the same on mine and report back immediately with results. I have the problem each and every day and it's exactly as you describe. It abruptly starts and stops with the AC system.

KenRLX

I'll get a couple more pics up in a few days. But,, BOM is about 4ft of 5/16 ID fuel line hose and 4ft of 5/8 ID heater hose from the local auto parts store. To give it a try, some nylon tie wraps (either 4 or 8 inches) from the electrical department of the local hardware store. That's it.


Then slit the hose on one side so it can be wrapped around the AC tubing. (5/16 hose over the smaller High pressure side, and the 5/8 hose over the larger low pressure side of the system) I found a box cutter does well to slit the hose (used carefully!!!). Then looking at the metal AC tubing do some rough measurements/estimates of the length of the sections that are reasonably straight, cut a hose segment to about that length, wrap around the AC tubing and cinch up with a few tie wraps.


I wasn't sure how extensive it needed to be, so any reasonably straight section of AC metal tube longer than about 3 inches got a piece of hose wrapped around. It doesn't seem important to accurately measure the lengths, as the bends are not covered by the hose segments.


Start from the firewall, working towards the front of the car - once you have most of the sections of the larger AC piping covered and several sections of the smaller high pressure side covered, go for a test drive!


If it works for you, then at some time some high temperature ETFE tie wraps (one place to obtain is amazon,, blue in color made by Hellerman Tyton) could be substituted for longevity of the fix. This type of tie wrap is rather more pricey than the local hardware store version, but still not terrible.


And good luck with this.. I am anxious to hear if this type of solution works for others with this particular problem.

KenRLX

Here some pics detailing the 'damping' of the AC hoses. For the type of AC moan that was on this car, the fix completely stopped the noise.

The blue tie wraps are made from ETFE (like a Teflon) to withstand the underhood temps long term.

wstr75

Ken, thanks for the excellent pictures and great engineering/trouble-shooting work, too!

What length tie wraps did you use? I looked up ETFE tie wraps on Amazon and found one company that made them. One package set was about $22. The other sets were in the $58 range and higher as I recall. Granted, they were being sold 50 or 100 to a package. See Amazon link below for the sizes sold:
Robot Check

miner

Have you sent your fix to Acura Client Services to show them how real troubleshooting and fixes are done? Great job on your end in getting this done.

George Knighton

Thank you very much for sharing this information. :-)

TampaRLX-SH

....along with a warranty repair bill for the future TSB. I believe they charge around $65 per hour for non complex warranty work, plus parts.

KenRLX

The tie wraps used are 4 inchers, and go for about 20 bucks per hundred. They did get around the larger heater hose well, but not with a lot of extra. The longer (8 inch) tie wraps would work too, but for more $$. The ETFE material itself is not cheap.

mgalbr22

Ken
Not sure how rigid this hose material is, but just wondering whether the twist ties are even necessary. If the hose is stiff enough, where could it go?! Of course, maybe it needs to be really snug on the ac lines.
Without the cost and hassle of the ties, the fix would be much easier.
What do you think?

KenRLX

I would give it a try without the tie wraps. It's like a guitar string or tuning fork - just trying to dampen the metal AC tubes so they don't 'ring'. Just slip the hose segments over the metal AC tubes similar to the pics.. it may be enough. I took the route of making sure there was some pressure applied to the hose material - but it may not be needed. Then, if you wish, the tie wraps can be added at any later date.

R. White

Not sure if it the same thing, but after 30 to 45 minutes of driving, I notice a high pitched noise coming from the ac fan. If I shut off the ac, it goes away.

Of course, I couldn't duplicate it for the dealer.

'14 RLX Tech

George Knighton

That's disappointing. Your dealer should already be aware that this is a little problem that people need to look out for.

There's a sticky thread with the TSB number that you can give him.

holografique

It is the same problem, and not created by the fan, but by the issues Ken has identified.

I've had the same problem in my RLX since several months after getting it. I didn't get a chance to implement the fix Ken provided prior to the accident.

So as soon as I get mine back from the shop, I will be implementing this pronto. One of the biggest annoyances I have with the RLX. Especially considering how quiet the interior is, you can really hear the problem.

holografique

I plan to try and implement this fix over this weekend. stay tuned...

pgeorg

If i have time next week, i will try it also. Please let us know.

EE4Life

See the following Acura Tech Line Summary Article:

BTS161202
High-Pitched Whine with A/C Running
Affected Vehicles: 2014-17 RLX
http://www.urvi.net/forumfiles/SB/BTS161202.PDF
http://techinfo.honda.com/rjanisis/p.../BTS161202.PDF

holografique

Lol. 3-years later and you're just now taking a look at this Acura?

Here, let us help your wonderful engineering team figure this one out for you on your flagship:

https://acurazine.com/forums/third-generation-rlx-2013-412/ac-whine-not-sure-how-say-931367/page2/

Complete with a video.

KenRLX

This is hilarious!!!!!
This is somewhat of an old thread, but there is some relatively new news from Acura.

The latest blurb from Acura (EEforlife link two posts previous), now dated March 2017, says DO NOT break the AC lines and do any repairs, it WILL NOT FIX the AC moan problem. Problem still under study.

I have told Acura verbally and specifically in writing about the actual 'fix', and it was extremely well documented here by holografique.
Acura is still supposedly still scratching their heads, or hiding them in the sand until the warranty periods expire.

holografique

^ unbelievable. absolutely unbelievable.

EE4Life

See TSB 17-032 - A/C High-Pitched Whine in the TSB sticky thread.