Intermittent rattle related to AC - struggling to diagnose exactly

F

Fabiantir

Member
Hi all

Got a 2006 E86 that has an intermittent rattle. I am sure it is something to do with the AC as it comes when the AC engages and goes when the AC turns off. It doesn't seem to impact the AC functioning, and from inside the cabin it sounds like it's coming from the front left of the car.

I thought that it was either the AC pulley or alternator going bad so yesterday I took the belt off (what a pain in the arse that is!) to turn all the pulleys by hand and see if I could narrow it down.

The alternator pulley is smooth, no wobbles, clutch seems to be fine. The tensioner pulley is nice and smooth. The AC pulley also appears to be smooth. I couldn't feel any grinding or play in any of them.

I don't want to fire up the parts cannon just yet, so looking to get some ideas on how to find out exactly what is causing it.

Any input appreciated, thanks a lot in advance
 
The AC pulley turns all the time, but it is only when you select the AC that it engages the clutch to turn the compressor. So you've not really checked that out. Your description certainly fits with it being an issue internally with the compressor.
 
Ah thanks guys, that makes more sense. Forgive the potentially silly question, but is the compressor bearing something that can be replaced relatively easily or would be easier to just replace the whole compressor and be done with it?
 
Fabiantir said:
Ah thanks guys, that makes more sense. Forgive the potentially silly question, but is the compressor bearing something that can be replaced relatively easily or would be easier to just replace the whole compressor and be done with it?
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I haven't done one, but I suspect the compressor would have to come out to do the bearing, so why not then fit a recon one?
 
If you still have the belt off, you'll be able to engage the compressor by sending 12v into the single plug on there - which will let you turn the compressor by hand as if the AC was turned on - might help troubleshooting?

Some BMW models have replaceable clutches (I did my R53's for example, recently after the wire frayed - didn't need to degas or remove the compressor either) - which car/engine do you have?
 
enuff_zed said:
I haven't done one, but I suspect the compressor would have to come out to do the bearing, so why not then fit a recon one?
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This is what I'm thinking - seem to be some alright options on ebay. My coupe just passed 166k so I wouldn't be surprised if it's just age related

TriggerFish said:
If you still have the belt off, you'll be able to engage the compressor by sending 12v into the single plug on there - which will let you turn the compressor by hand as if the AC was turned on - might help troubleshooting?

Some BMW models have replaceable clutches (I did my R53's for example, recently after the wire frayed - didn't need to degas or remove the compressor either) - which car/engine do you have?
Click to expand...

It's an E86 so N52B30
 
I’ll be replacing the compressor clutch when I have the coupe back at home, I have already bought the part that should fit. There should be enough space to do it without needing to remove the compressor.
 
Before you go ripping your a/c system apart check it's not the cover plate(s) on the front of the compressor clutch when the clutch is engaged. They can become loose in their 'pins' and rattle. It shouldn't affect the clutch pulling in if it is that.
 
Pondy said:
Before you go ripping your a/c system apart check it's not the cover plate(s) on the front of the compressor clutch when the clutch is engaged. They can become loose in their 'pins' and rattle. It shouldn't affect the clutch pulling in if it is that.
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Bit of a late reply here! Thanks for this tip - I'll be having the car up on stands next weekend so will investigate if it's this. I hope it is cos a cover plate sounds a lot simpler than pulling out the clutch/bearing etc
 
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