A/C whining noise with revs

[Allworth]

Hi all,
There is a whining noise coming from A/C system that fluctuates with engine revs, when above 2,000 it seems to disappear. As soon as I press A/C button off - noise dissapears, even if fan is working. Had an AUC sensor error, replaced the sensor - error gone but the noise still there, so unrelated.

I am suspecting that A/C is giving extra load on V-belt thus wearing tension pulley could be the culprit.

Any thoughts?

(I should add that I have 118k miles on the odometer)

[Portly]

My A/C has been making the whiny-belt noise since I purchased the car with 30k miles (50,000 km) on it. I now have 120k miles (190,000 km) and, to my astonishment, the A/C is still working fine. I kinda think that's "just how it is" with this car, though perhaps others have different experiences.

[gregthegr8]

I'll chime in too as I've been researching this of late and seem to hear/read 3-4 various things people say are the cause/fix.

It's only in recent weeks, at about 44k miles, that my a/c has started to make a slight additional whine/whir/not sure what to call it. Increases with RPM, and goes away if I turn the a/c fan or a/c button off (fan still blows). Haven't looked under the hood with it on/off yet to check it out. Seems like several people have had various things replaced to deal with this only to still have it there and many reports of dealerships just saying it's "normal" and "how it is."

It's slightly annoying, but not sure how big of a deal it is or if left alone/not addressed, if it'll develop into something worse. My biggest fear is some shop saying it needs a new condenser or pulley or belt, I pay through the teeth, and the noise is still there. I've seen other reported fixes of recharging the system, adding a/c oil to the condenser or something, etc.

Any input or an a/c support group would be greatly appreciated.

[maxwmiller]

Allworth,
Turning "on" and "off" the A/C button engages and disengages the compressor. "On" puts additional load on the engine to run the A/C cooling system, which increases RPM at idle. It is normal for A/C "on" to cause a constant, noticeable but not overwhelmingly loud noise, especially under 2000 RPM.

Assuming your serpentine belts are in good shape and you have an appropriate amount of refrigerant in your system, there's not a cause for concern. It is almost a guarantee for an A/C system to get noisier as it ages.

Gregthegr8,
In general, the A/C system really doesn't need much maintenance. Belts are cheap and easy to DIY, replace them every 4 yrs/50k miles. If the A/C won't blow cold, look into getting a recharge. Otherwise unless something fails, there is no need to throw money at a slightly noisy but otherwise perfectly functional system.

Also I cannot stress this enough, do not DIY an A/C recharge! Yes, auto parts stores sell recharge kits. They usually forget to mention that these come with a significant risk of "overcharging" the system, which will destroy it in seconds and cost $1000s to repair. Just go to a local shop.

[gregthegr8]

Originally Posted by maxwmiller

Gregthegr8,
In general, the A/C system really doesn't need much maintenance. Belts are cheap and easy to DIY, replace them every 4 yrs/50k miles. If the A/C won't blow cold, look into getting a recharge. Otherwise unless something fails, there is no need to throw money at a slightly noisy but otherwise perfectly functional system.

Also I cannot stress this enough, do not DIY an A/C recharge! Yes, auto parts stores sell recharge kits. They usually forget to mention that these come with a significant risk of "overcharging" the system, which will destroy it in seconds and cost $1000s to repair. Just go to a local shop.

Thanks for the advice. I haven't investigated it too far yet, though it is getting a lil louder I think, but will check it out under the hood with a/c off and then on to see if i can locate where the noise may be coming from such as a belt or pulley. Belts definitely have NOT been replaced since I've had it (almost 5 years) and it blows cold. And yes, I'd rather not throw/waste money at a slightly noisy thing, lest it might lead to some ultimately further and costlier damage down the road due to my procrastination or laziness.

[Allworth]

Just to take pulleys out of the equation;
I had to do a maintenance, because of a squeaky noise on a cold start, so replaced idle pulley and tensioner with a pulley. Squeaks gone, a/c still whining.