Whistle sound when A/C is running

[chitown1211]

Hello everyone,

I am getting a wierd whistling noise from under the engine. Only happens when the A/C is running.

Sounds kinda like a jet turbine. It comes on for a few seconds and dissappears. Happens a few times per hour mostly under acceleration.


I searched , but didn't find a specific solution to the problem.


Is this a "problem"? Has anyone expierienced this before?

 

[TheTurk]

dont know if its the same think but when i pulled out the my recirc. door off its place i started hearing kind of whistle your talking about so maybe you should give that a look
good luck !

 

[rdop02xlt]

I have the exact same noise. I can tell you its not related to the recirc door because its always made the noise whether the door was hung up or working properly (just fixed it last week). I think it is related to the compressor clutching in or out and the subsequent change in refrigerant flow/pressure.

 

[chitown1211]

I have the exact same noise. I can tell you its not related to the recirc door because its always made the noise whether the door was hung up or working properly (just fixed it last week). I think it is related to the compressor clutching in or out and the subsequent change in refrigerant flow/pressure.

Yeah it definitely sounds like a flow/pressure type deal to me. It seems to work fine though so I am not too concerned. I will report back if I ever find the cause or solution.

 

[jvano]

My X does the same thing. I don't know what it is, but I think it sounds cool, almost like a turbo lol

 

[57 t-bird]

Same thing on my 05 XLT V-8. Bought new January 05, a/c still as cold as the day I got it.

 

[chitown1211]

My X does the same thing. I don't know what it is, but I think it sounds cool, almost like a turbo lol

Thats a better description for the "sound" it makes. lol

 

[Argentimage]

Sometimes it sounds like a goast moaning or hooting, never fixed the issue on the X, mine does it too.

If your really into chasing this, start at the compressor and the condensor and chase each and every line back, look at all connections to see if they are isolated with rubber so there is not a ground part. After all that, you may or may not have it fixed.

Now for the unspoken obvious, you can't isolate the compressor from the engine with rubber as its driven on the FEAD.

If one of the tubes it touching the body, that could be the ground path, you will have to go line by line, especially important from past experience is the drier bottle and wher the lines go into the dash panel. Also the air box or eval case inside could be slightly grounded.

The good news is that in December you don't hear it!

 

[gjblanchard]

my 05 4.0 does exactly the same thing. Always has and I've never had a problem with the AC.

 

[timbrendelaz]

Please don't kill me for resurrecting an old thread. I searched before posting like a good boy and came across this thread which mostly sums up my issue but I was wondering if I could bounce my particular issue off of you smart folks.

My 02 Explorer with the 4.6l V8 makes a very distinct whistle when the AC is engaged. I live in AZ so it is a necessity here but I can tell you that the noise goes away when the AC is off. It sounds like one of those plastic tubes that kids swing above their heads to make that whistle sound. The weird thing for me is that when it whistles I also lose power. Not a lot of power but definitely noticeable.

I replaced the IAC valve a few weeks ago because it needed it and I was hoping that would fix the whistle based on other posts here I've read about the issue. (BTW, never buy Duralast parts. Ended up buying 2 valves because I had issues and went to Motrocraft).

The AC was serviced and recharged and blows very cold. I have the typical issues with the blend door actuator and fresh air door but everything other than that seems to work. All the dash vents blow properly, though the driver vent near the door feels like it barely blows.

Anyway, as I've mentioned it only happens when the AC is on. When the AC is off I have absolutely no whistles or loss of power. I like to consider myself mostly knowledgeable about auto repairs but this one has me stumped. A mechanic friend (service writer now) told me without seeing it that it may be the AC compressor or clutch going out and putting additional strain on the engine when it engages but I personally think that would cause more of a squealing sound, rather than the whistle I am hearing. Any ideas would be greatly appreciated. Thanks in advance.

 

[Number4]

I’m pretty sure this is caused by the refrigerant moving through the system. It’s the sound air makes passing over the lip of something. Not unlike blowing across the top of a coke bottle.

Mines done this off an on, even after having the system evac and refilled. I’m guessing the system is low, but not too low to show bad pressures. Now mine isn’t as cool and does it more often. So I’ve clearly been loosing refrigerant.

Mines always done it on acceleration and mainly when the system has just recently been turned on.

Also seems to more an issue for people with the 4.6 more than the 4.0.

 

[timbrendelaz]

I get that, I really do but 2 thoughts I have make it seem like that couldn't be it. First, I literally just had the refrigerant charged at a shop so I know it was done correctly.... and 2, I lose power when I hear it whistle. I wouldn't think the normal flow of refrigerant would cause a power loss. It whistles and it loses power, then it stops whistling and I regain the power. This all happens, for example when taking off from a stop light and getting up to speed. It's definitely outside the vehicle too because people can hear it outside. This is driving me nuts, lol

 

[timbrendelaz]

Does anyone think the "whistle" I'm hearing could actually be a bad bearing on the compressor clutch/hardware? Maybe I'm hearing a squeal or screech that sounds like a whistle when it engages. That could explain the slight power loss. Maybe it's just adding extra strain when it engages?

I know it's coming from outside the vehicle though because it's loud enough for other people to hear. I swear it sounds just like one of those tubes that kids swing around in circle over their heads that make that high pitched whistle sound.

 

[Number Twelve]

When I was studying for my Florida State test in A/C I did the math for a typical car. The answer was 0.5 to 5.0 HP depending on outdoor conditions. Phoenix is obviously a 5 HP place! If you think you're losing about 5 HP there is nothing wrong.

 

[Number4]

My ac went completely warm two days ago. I vacuumed and refilled late last night. Still have the whistle on a full system today.