AC noise/rattle at idle??

[Russell]

Often I notice a bit more vibration/noise/rattle when the ac is on at idle. especially when the weather is very hot. AC belt and idler pully and tensioner replaced the spring. Other belt and pullys are at least 30,000 miles old.

Any thoughts?

Is my compressor wearing out? In 4 years it has never been recharged yet cools well. Can it be just low and laboring more? Not a major problem YET :)

TIA

[Russell]

Any thoughts?

[tim]

Sounds like the bearing may be wearing out. My friend's 528 is doing the same thing.

[bsell]

Sounds like the bearing may be wearing out. My friend's 528 is doing the same thing.

Which bearing are you talking about, the one that lets the pulley spin without spinning the compressor or the compressor's internal bearings?

If the pulley bearing goes bad, the symptoms (noise, vibration) happen with the a/c off. This quickly becomes a 'walk' condition if your a/c turns off (or doesn't work!) during normal cycling causing the pulley to spin and heat up the trashed bearing. Once the bearing seizes, there goes the a/c belt and any other belt it decides to take with it, hence the 'walk' designation.

If the compressor has bad bearings or is going south, the symptoms (noise, vibration) happen when the compressor is running. In other words, it is possible for the pulley bearing to be fine yet the compressor itself is garbage. Plus you can drive the car for miles like this as long as you don't turn on the a/c...

[bsell]

Often I notice a bit more vibration/noise/rattle when the ac is on at idle. especially when the weather is very hot. AC belt and idler pully and tensioner replaced the spring. Other belt and pullys are at least 30,000 miles old.

Any thoughts?

Is my compressor wearing out? In 4 years it has never been recharged yet cools well. Can it be just low and laboring more? Not a major problem YET :)

TIA

Can you get a set of gauges on the a/c system to see what the high side is doing? You say the symptoms are worse when it is hotter (higher high side readings). I wonder if the high side is getting too high due to a lack of airflow over the condensor? Do you have a bad aux fan or a lazy fan clutch? Or is your compressor getting a weak cylinder?

Brian

[Russell]

good points. However, I know nothing about AC. Even so, I can hear the aux fan run and the ac clutch switch off and on. I think I will have my indy check it out on the 10th when they service the trany.

[tim]

Which bearing are you talking about, the one that lets the pulley spin without spinning the compressor or the compressor's internal bearings?

...

I meant the internal ones. I'm not an expert, but in my friend's case, he had the same symptoms- idle with ac on it sounded like there was a marble or something caught in there. It made a real racket, and it wasn't as bad at higher RPM, and wasn't there at all when the AC was off. First off, I replaced his belt and tensioner to no avail. Next I thought it was the magnetic clutch (the thing that lets the pulley spin), but i put a stethescope on the housing and it was clearly coming from the compressor itself. We know a guy that gave us a used, but working unit for $200. New I think they run about $500.

I hope that helps.