Sounds like a failed A/C compressor, right?

[JQADDINGMACHINE]

2005 audi s4

www.youtube.com/watch?v=10igDKZV1po

Just got the car running, and it does this shit as i pull into the DMV for inspection lol. Sound is coming from lower drivers side and I can feel it really well when touching one of the A/C lines down there.

How much of a bitch is this to replace? do i have to pull the whole rad support and everything off?

[mace115]

Lots of good info in this thread.
http://www.audizine.com/forum/showth...n-Next-Step(s)

Yes, whole support has to come off. I personally haven't had to do mine yet (91K Miles) but everything seemed pretty straight forward when I read through some of the DIY's out there.

[AllroadMass]

I'm assuming your econ light comes on when you turn on your ac, correct?

The last clear image on the video is the power steering pump and in front of that sits the compressor. I was trying to pause the video to see if the drive shaft was spinning but didn't get a clear look. If you look to the right of the engine support bracket, you should see a shaft that drives the compressor. Just did mine a few months ago and there's a ton of resources and helpful people at this forum. Let me know if I can help.

Sent from my Nexus 7 using Audizine mobile app

[JQADDINGMACHINE]

I'm assuming your econ light comes on when you turn on your ac, correct?

The last clear image on the video is the power steering pump and in front of that sits the compressor. I was trying to pause the video to see if the drive shaft was spinning but didn't get a clear look. If you look to the right of the engine support bracket, you should see a shaft that drives the compressor. Just did mine a few months ago and there's a ton of resources and helpful people at this forum. Let me know if I can help.

Sent from my Nexus 7 using Audizine mobile app

Now I feel stupid. the shaft is not spinning and the noise does not go away when i turn the AC on or off. it's constant, gets louder with RPM, turning the wheel left and right has no change.

is the clutch for the AC compressor ON the compressor or is it in that area of the engine with the gear drive?

I can DEFINITELY feel it when i touch this AC line:


Edit: and no i did not see an Econ light on by the HVAC controls

nothing on my HVAC control panel makes the sound change, on/off/econ mode


oh jeez that shaft is supposed to spin at all times isn't it

oh lord

[neilpaku]

There is no clutch. The compressor is constantly driven by the PTO. If the shaft is not turning when the engine is running, suspect a broken PTO shaft minimum (you should hope that's all it is because that can hopefully be fixed without an engine removal). Undo the shaft to compressor using your 17 and 19mm wrenches, pull the shaft out if it's broken, or remove the compressor drive plate (six screws holding the boss that the PTO shaft screws into) then pull the shaft out, then get a magnet and attempt to pull the broken stub out of the splined socket. If the broken stub comes out, breathe a sigh of relief, order a new shaft, rubber boot, the 36mm Oetiker single ear clamp, and possibly a new ac compressor (if the shaft broke, it might be because the compressor gave up). If the shaft comes out with an unbroken end, then you'll need to open up the PTO drive, which will require an engine removal. If you have to do that, then do the timing chain guide service at that time.
I can see the shaft right at 0.22 (about halfway through that second just as you pass the engine mount (large silver round object) but the video is too quick to be able to see if it's turning, just to confirm that you're looking at the right thing.

[AllroadMass]

Don't run the car if the shaft isn't spinning!

The shaft should always spin no matter if you have the ac on or not. The compressor is driving by the shaft which must connect to a gear unit due to the picture attached. The right side of the picture (with the spline) connects to the engine timing. If the compressor seized I would imagine that either the shaft would snapped or the spline would round off. Worst case would be the gear unit inside the timing components is rounded off.



Sounds like you're going to have to take some things apart to get a better look at the compressor and shaft.

[AllroadMass]

There is no clutch. The compressor is constantly driven by the PTO. If the shaft is not turning when the engine is running, suspect a broken PTO shaft minimum (you should hope that's all it is because that can hopefully be fixed without an engine removal). Undo the shaft to compressor using your 17 and 19mm wrenches, pull the shaft out if it's broken, or remove the compressor drive plate (six screws holding the boss that the PTO shaft screws into) then pull the shaft out, then get a magnet and attempt to pull the broken stub out of the splined socket. If the broken stub comes out, breathe a sigh of relief, order a new shaft, rubber boot, the 36mm Oetiker single ear clamp, and possibly a new ac compressor (if the shaft broke, it might be because the compressor gave up). If the shaft comes out with an unbroken end, then you'll need to open up the PTO drive, which will require an engine removal. If you have to do that, then do the timing chain guide service at that time.
I can see the shaft right at 0.22 (about halfway through that second just as you pass the engine mount (large silver round object) but the video is too quick to be able to see if it's turning, just to confirm that you're looking at the right thing.

How did you type so god damn fast! Me and my fat fingers tried but I just couldn't do it.

[JQADDINGMACHINE]

thanks for all the quick replies tonight guys, i'm going to throw it up on the lift when I get off work tomorrow and try to pull that shaft out.

[AllroadMass]

thanks for all the quick replies tonight guys, i'm going to throw it up on the lift when I get off work tomorrow and try to pull that shaft out.

Woohoo,good luck!

Sent from my Nexus 7 using Audizine mobile app

[JQADDINGMACHINE]

Got upset about it so I went out and pulled it out tonight instead.





Before i pulled it out it spun pretty freely (with the little chirping sound) which you can see in the video but after i had the shaft out, i could put it back in and if i held it at the correct depth it grabbed and i couldn't turn it by hand.

any chance it looks like the shaft is rounded instead of the gear drive? I spun the compressor by hand after pulling the shaft out and it is whisper quiet and smooth.

looking at the pictures a little closer it does look pretty shitty inside that gear


edit: I'm still not sure why this happened..? the AC compressor spins well enough it's definitely not seized or anything. could it be overcharged or something?

[REVOofRustler]

I can't say whether the shaft looks good or not, but definitely take the drive plate off the compressor and check to make sure everything is in tact. The drive mechanism is made so that if the compressor seizes, the drive mechanism fails so that the shaft can keep spinning. Here's what mine looked like on my old compressor that had seized.



This thread is also a goldmine of info for the AC compressors in our cars: http://www.audizine.com/forum/showth...pressor-Issues

[2004B6S4]

Sounds like your drive gear is stripped out, sorry to hear that. I've heard of that happening to the power steering drive gear but never the A/C. Judging by your picture, rust seems to be what causes it to strip out so that's good to know. Sorry to say you'd have to pull the engine out and take off the timing covers and one of the chains and then the accessory drive gear unit in order to replace the stripped part. maaaaybe you can come up with some way to get it to catch on the remaining splines... maybe put a spacer between the shaft and the compressor to make it stick out a little farther? I know there aren't many threads on the end of that shaft so you don't have much to work with but it's worth a try. unless you need to do the timing work anyways.

[neilpaku]

Major cause of this is that the splines are/were not lubricated. Manual shows that the splines need to be greased when being fitted. Was there a rubber boot over the socket? If not, then that's why it got dry and thus wore. I just replaced the boot on mine as the old one was getting soft and cracked (135k). Take a look at this to see the arrangement: http://nemiga.com/cat_spares/etka/audi/a4q/249u/260260/

The good news is that there are no broken shaft ends in there to have to pull out.

Before tearing into an engine removal, first thing I'd do is get the vacuum cleaner in the socket with a pick and clean up the splines and determine just how worn they are. "In theory", if the Audi designers used good design principles, the shaft should be a softer material than the socket and so should wear first. If so, the socket should not be "much" worn, and a new shaft will be sufficient. That said, how long did you run it with the spline slipping (that's what the zipper noise was) because under those conditions, the socket will wear some.

The only way to know though is to clean it up, measure the ID of the spline tips compared to the spline valleys in the socket to see how much "teeth" you have left on the socket. Compare that spline height to the spline height on the new shaft. If you have at least 50% engagement depth, then you can probably get away with not replacing the socket (engine removal) but instead swap out the shaft at say 30-50k miles as it wears.
You must grease the splines and fit a boot. The boot (079260753B) is secured with a 34.6mm Oetiker clamp (N10207701). You can close the clamp using a regular end snipping pliers such as you'd find at Home Depot and round off the sharp edges. I bought the $45 kit on ebay which includes all the sizes up to 24-ish and the pliers because I had other single ear clamps to fit. The shaft is 079260095D
(Note: after fitting the boot, you can still fit and remove the shaft - it just pushes through the boot. Regular grease is fine to use, or silicon grease or whatever you have laying around)

[JQADDINGMACHINE]

I ran the car like this for a total of about 20 minutes. there was a boot on it, but no clamp. if the socket is bad, can i just leave the shaft out until i have time to gather parts and pull the engine? when i get home from work today i will try and clean it up to see how bad it is.

[neilpaku]

I'm seeing an oil seal on that shaft so it should be ok. Start the engine up and look for a leak. If not, then drive it around the block and check again. If no leak, then you're probably good to go without the shaft. http://nemiga.com/cat_spares/etka/audi/a4q/249u/109520/

[2004B6S4]

yep you can run it without the shaft installed, the a/c is the only thing affected by that. I did that for 2 years

edit - I mentioned in my earlier post it looks to me like the splines in the gear are stripped, and I think the splines on the shaft look ok. But it's hard to tell just from pictures so neilpaku had a good suggestion to clean it up better and check to see if a new shaft might work for you. that would a better option than an engine pull for sure

[JQADDINGMACHINE]

Again, cant thank you guys enough for helping me work through this. My dad wants garage time for his camaro so I really wasn't trying to have to pull the engine to get this thing running again.

for anyone who comes across this thread later with a similar issue, this was my problem;


I guess the only question now is why it did this? I wasn't even pushing the car as the noise started (just coasting up to a red light). the compressor isn't seized, I looked inside and my drive mechanism looks fine unlike REVOofRustler's. Could an overcharged system do this? maybe making the compressor work too hard? I hooked up one of those autozone AC cans just to use the gauge (i had figured it had a leak, lost oil/refrigerant and seized) and the gauge showed it deep into the red area. I don't know what pressure that is but it can't be good.

regardless I hope to have what i need by springtime so I can get A/C when the heat comes back

[2004B6S4]

was yours missing the rubber boot (#6 in this link from above http://nemiga.com/cat_spares/etka/audi/a4q/249u/260260/ )? The early models didn't have those. My guess is that you had water getting in there and over time the grease got washed out and the splines rusted and eventually the rust weakened them enough to cause this.

I'm guessing that broken guides might contribute as well (broken guide causes slack in one chain, when you start up the engine and it tightens up that slack it causes a sudden jerk on the rest of the chains/gears rather than a fluid transfer of power). Mine went during a warm start and the shaft itself is what broke (not the mechanism in revoofrustler's pic which was designed to be the weak point that breaks). This was on a really hot day after running the a/c for a long time so there would've been a lot of pressure in the a/c system. After taking it apart I found that the A/C compressor was not seized at all. My theory is that the resistance from the high pressure in the system, combined with a sudden strong jerk on the shaft, is what caused it to break and that it wouldn't have happened if the timing system was ok. One way to picture this is to imagine you have a wrench on the end of the shaft instead of the drive gear - an intact timing system would drive the gear with smooth, even power like a hand wrench whereas one with broken guides would drive it more like an impact wrench because of the sudden jerk when it takes up slack. Mine was an early model without the boot and it had 0 rust but I live in a very dry climate. I'm guessing the splines were the weak point in your case because of rust

[JQADDINGMACHINE]

It did have a boot and it was in place, but there was no clamp on it, I just had to tug it off. I could imagine water getting in there. I don't think it would be your broken guide theory because the shaft failed at idle after it had warmed up, and I don't have any kind of cold start chain rattle whatsoever. I think this car was originally from Colorado, spent some time in New York and Pennsylvania, and now it's going to spend some time in Delaware.

This car does have high miles though (139,000). I'm just going to assume all the grease dried up/worked its way out years ago and it's been decaying from rust ever since.

[neilpaku]

It "looks" like the photo shows that the socket's splines are mostly worn down, judging by the ID of the opening relative to the spline height. There's just a tiny bit of full height spline at the far end. After pulling the engine, removing the back cover, you can unbolt the PTO drive assembly and replace that socket (hours to pull engine, 3 minutes to replace the socket unfortunately).

[teutoned]

...if the Audi designers used good design principles...

good one!

[Atttto]

I decided to keep this tread going instead of making a new one.

I have an 2005 A6 With 4.2L BAT motor and about 5 months ago i changed all of the timing chains and guide rails, but now the a/c stopped working with "squeaking noise" so i pulled the drive shaft for the a/c pump and the splines are almost completly stripped, but the pump is loose and seems ok.

How likely is it that the drive shaft is my only problem?