I have used a mechanic stethoscope to try and diagnose bearing noises before. Unsure if it would be as helpful with a whine. Does the whine increase / decrease when turning the wheel while the vehicle is stopped?
I’ve tried using the stethoscope and it seems that the sound is slightly stronger on the compressor than the alternator. The whine seems to decrease a bit when the wheel is turned (while the wheel is stopped).
I’ll try to the approach of taking off the belt and assessing the pulleys by hand.
AC clutch…will look into that. Hopefully that’s cheaperthan replacing the entire compressor.
Yeah, the o-rings looked worn so I’m happy that they were replaced in any case.
Just an idea, but if you did not replace the belt tensioner, it’s old now and won’t keep the proper tension. Three years ago on my 2006 Nissan, I was still getting noises after just replacing the belt. Replacing the belt tensioner fixed that, and also smoothed out the car’s engine at idle. Still running great today.
A worn out serpentine belt could cause it too. It’s usually possible to completely remove the belt and start the engine, letting it idle for 10 seconds or so. If that prevents the noise you at least know it is something to do w/the belt or something on the belt loop. Caution: removing the belt might prevent the water pump from working, so only do this on a cold engine and only for a few seconds.
I removed the belt and inspected all of the pulleys. None of them made any loud noises when they were spinned by hand, so it doesn’t appear to be the bearings on the pulley that’s making the noise, unless they only make the noise when they are spinning really fast. The auto tensioner pulley showed some signs of wear and tear e.g. black scruff marks. The belt seemed fine. I did not see any signs of wear and tear on the belt.
I put the belt back on and turned on the car and investigated further with my mechanics stethoscope.
I noticed the whining sound starts as soon as the ac fan (at the front of the car) turns off. When I turn on the ac then the sound disappears as the fans turn on, however, even with the ac still on, the sound reappears when the fans stop spinning.
The sound seems to be coming from the right side of the compressor. This is where I biggest difference in the intensity of the sound seems to be i.e. when turning the ac on and off.
The tensioner is basically a metal spring that after 12 years of use has suffered metal fatigue, and is not applying the proper pressure anymore. This can cause some misalignment and stress the other components. If you can change it yourself, a good Gates one can be had for $70 or so. I am sure you will notice an improvement.
Good stuff. Hope it goes ok. On my Nissan it was a little awkward to get at, but doable and resolved my belt issues. Sometimes you can find a Youtube video of the job being done on your car model. Sure enough.
Yeah, I replaced the auto tensioner and it did not solve the problem. The noise is a little bit reduced in intensity but it still persists especially while accelerating the car. Using my stethoscope, I can’t tell if it is the alternator or compressor, since the noise is heard at both of these locations.