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AC Compressor casting cracked..what caused?


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Found oil on floor....which lead to finding drips on lower shroud. Was thinking it was more power steering leak but fluid was green. Engine had not been run for 24 hours but was able to see bubbles on the casting of the AC unit. If it was not bubbling would never have seen the crack. Lucky it was not on top or on a side. What could lead to this casting crack? Can I order a replacement compressor and have a generc shop evacuate and refill with 134 after it is installed? What is the best course of action? I can not drive it to a dealer as I am over 200 miles away and I believe that when all of that PAG oil leakes out of the compressor it will seize. And thats a problem on vehicles with serpentine belts. I miss multiple belts as one can make it home by cutting the belt connected to a seized ac.

I will probably be nominated to replace this ac unit...I see it appears to be kinda close to get at...difficult to remove / replace...any tips..advice appreciated. Trying to post pic but says it is oversized even though it is under 2 megs. Will try adding.

Thx,

John

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If you go into the heater control and press the ECON button - it turns the AC compressor off. I believe it does this by disengaging an electronic clutch on the front of the compressor. As long as the pully is turning freely you should be able to drive it..

Can someone confirm the compressor has the electronic clutch?

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Assuming they didn't have a specific compressor for the turbo.. it's a Denso compressor and from photos/descriptions on the Interwebz does have a magnetic electronic clutch on it.

http://www.automotix.net/usedautoparts/2006-porsche-cayenne-ac_compressor-product-g62916448h.html?gclid=CLfO_svH4bcCFYWe4AodEE0AzQ

com_category_dp.jpg

http://www.discountacparts.com/addtocart~year~2006~make~Porsche~model~Cayenne~descript~A-C_Compressor~part~60-01801.asp

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That is correct, it, as in most all automobile AC compressors has an electric clutch at the front which the pulley bolts too. If you run the climate control panel in Econ and NOT auto, the compressor will remain disengaged and the pulley will turn freely.

P.S. I usually run my panel in Econ if the A/C is not needed for cooling or demisting. Saves on the system but you should always turn it on for at least 5 minutes every couple of weeks to circulate the freon and with it the oil to keep everything lubricated, especially the seals.

Edited by hahnmgh63
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Guys,

Thanks for the info..much appreciated. I have not wrestled with an AC replace in any car as of yet. I know there are several components besides compressor. When I replace compressor do I need to replace the other associates as well? ie drier and etc. It appeared that the nose had to be pulled off truck to replace some of the ac stuff. I would rather not have to do those other parts but I also do not know what would make a compressor casting crack. Was or is it something related to other components in ac system...I have no idea?

Also, I am not a wealthy dude. I took a crack at a cayenne as a gamble with 85 k on it. Always wanted one and don't ever gamble otherwise. So far I have had to endure some pricey clean up on this used rig but overall love it and think that the repairs should slow down. I do want to contribute to this web site because the information is invaluable from you guys. I do not want to be a cheap skate and would like to know what an appropriate donation should be.

Did I mention I love driving this rig ..wife loves it too. And that is just for regular puttering around kind of stuff...I do have a litre class sport bike and have ridden for many years. I have yet to push the cayenne ...just kinda of felt its presence on occasion...and it feels good:].

Tried to upload 1.6 meg pic again...no go.

BTW the AC unit is a denso

Thanks for the ECON setting info too. That puts my mind at ease for driving it. Was thinking about unplugging the wire connector to the ac but was wondering how many computer error cyclones would be created if I did that.

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Attention here, Cayenne do not use AC compressors with a magnetic clutch, The used compressors runs continuously and the pressure control is done in a different way. Take note of such compressors should never run with too little or no refrigerant, otherwise they break down due to lack of lubrication.

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Interesting Post...

2005 CS manual, page 136, Button "N" ECON button (air-conditioning compressor off/on)... so if the compressor is always "on", are we really improving on fuel economy by using ECON?

So is the statement "ECON button (air-conditioning compressor off/on)" false?

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I have a 2006 CTTS and just put it up on the lift, started it up with the A/C running. With the belly pan off I could see the compressor clutch engaging and disengaging every once in a while. I then switched on the Econ button and watched the compressor and their was no engagment of the clutch, just freewheeling so I would say it is as standard of and A/C auto system as you can find, no continuous operation which would make sense, it has to be able to switch off due to temp/pressure changes.

P.S. Looks to be the identical compressor in my 2003 Audi. Both Denso's.

Edited by hahnmgh63
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The Cayenne V8 Turbo MY04 for "Nylon" has ID9L as engine code and using a compressor without magnetic clutch, part # starting with 948 ... the natural aspirating V8 with engine code ID9K uses the same.

The Cayenne V6 with engine code ID9J do have a compressor with magnetic clutch, part # starting with 955

The Turbo S did not exist yet. (MY04)

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Wish I could post a pic because the AC unit on this car looks like it has a clutch. 2004 cayenne turbo. When I got this truck I had a bit of a falling out with the seller because he represented himself as selling a car he owned but leased...turned out he bought at auction and resold. So Info on history is sketchy. I do have pretty good service records on it..just not complete. I do not have the record for the a/c replace but this fellow claimed that the a/c compressor had been replaced. It does look pretty new. We are up in northern Minnesota and the very first time (last week...been a very late spring) this a/c would have engaged freon it popped the casting. So something was / is screwed up. Unit in it now is a denso. My wife was driving when the service now light came on. I thought it was simply the service in 2500 miles telling us that those 2500 miles were up. Now I am thinking the car knows the compressor is toast. I turned the temp to low and pushed econ button off and waited to see if I could feel engine drag from engage and for cold air to blow. I also looked to see if the black protrusion in front of the A/C pully that I assume is the clutched part would spin. No spin in either econ on or off mode. Also no cold air.

I called Carrosel porsche dealer in MSP and also Imola a semi indy. Both told me that I could drive it the 250 miles to the cities to have it repaired in econ mode. Imola told me that the Compressor was $314 and labor to replace is $220. I want to make sure I have a complete system so the advice on the drier and etc is much appreciated. The thing is if that compressor is spinning with the PAG oil leaked out of the crack it will seize unless it is not actually spinning.

Does anyone have any experience with Imola in Wayzata (MSP) Minnesota? I would like to use them and for the most part their reviews are good with occasional POed customer. I know grains of salt need to be considered.

Also saw a discussion on cooling fan. I had been hearing my fan run when it didn't seem that warm out or really necessary but that is guesswork. However, I did hear that fans should run as they do on my motorcycle after it has been shut off because they are electric. I have never had the fan run on cayenne after shut off.

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On a side note that may be entertaining, I had a '77 cutlass supreme in downtown Denver on Colfax ave just east of the capital building. Some of you may know what that area was like in those days. The expansion tank went off like a bomb under the hood. Scared the crap out of everyone on that block...but especially me cause I didn't know what it was for a while. This was in the early '80s.

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I don't want to start an argument here but the Porsche shop manual lists the repair portion of the HVAC system as MY2003-2008 so it sounds like they're the same to me? Where is Loren when we need him :)

As far as the repair you are correct to worry about just the compressor replacement. Whoever you have do the repair needs to inspect the compressor to make sure there wasn't any damage which may have left damaged pieces in the system. The Porsche repair manual does talk about flushing the system to purge it but I'm not sure what type of equipment they use but it may be worth a call to the dealer and to the indy your looking at to ask the question.

Edited by hahnmgh63
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This is a description of the compressor ops from the Tech manual. They also call the compressor a regulator in the same manual.

"The piston stroke can be continuously varied, based on the electricity strength change of the PWM signal. A large stroke for large (cooling agent) capacity demands and a smaller stroke for smaller capacity demands. The higher the pressure, the further the swash plate can swing out in the direction of the zero request and can decrease the capacity demand of the compressor. Because the compressor works with a variable capacity demand, it is not necessary to control the cooling capacity of the climate control over the on and off switch of a compressor relay. This means that the compressor is turning when enough cooling capacity is there, but can also work with zero requests. In this case the compressor will turn with no burden."

Edited by bigbuzuki
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Guys,

Thanks for the info here! This is not an arguement but a good discussion. The description of function out of the manual makes sense. Older tractors opperate somewhat similar with hydraulic pump. On My 68 4020 the hydraulic pump runs on standby pressure. Once a function (loader) is used the pressure drops from 1950 psi and the pump kicks on. On a Farmall 460 from the eraly 70's the pump always runs.

My only problem is this...can I drive that Pepper 250 miles to get the compressor changed? If it is not clutched then it spins and with that PAG compressor oil leaked out..that would be a no. However two different Porsche repair shops told me I could drive it with econ button on. I will be driving through fairly remote and seriously populated with mosquitos terrain. Don't want a compressor seizure and then have to find and pay a flat bed tow to bring me the rest of the way. Another possible scenario is that the current compressor on my 04 turbo may not even the correct one for that car. It cracked the casting first time it was called to supply cold air and maybe it is clutched. Whoever did the repair obviously screwed it up...just how bad is yet to be determined.

I will take some pics tonite and set the resolution lower and see if I can post them of the compressor pully, the crack and denso #s. I had posted pics before and it worked fine of power steering line the blew off in really cold weather.

Again..shop manual function description very much appreciated as well as looking right at it while running on the lift witness. We ..or I have a conundrum and your help is appreciated!

John

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My other option is to order the compressor, drier and valve ...ship them to me and have a local shop install. They have not touched a porsche ever. They are good and are an independant shop and are friends of mine so I trust them. I tried to get a compressor from NAPA but it is a Porsche part and can't be had through them. Although it looks like it is still just an ac system and as long as I get parts...they pull out the old, stick in the new, flush all the crud out and evacuate system then refill with 134...it should work ...no? I would replace myself but I have no way of evacuating...vaccum system. Thoughts? Quick look through e bay and this compressor appears to also be used on Audi....What about the Touareg. I think I found some thing on the net that stated that a v6 cayenne did have a clutched compressor while the v8s were not clutched. Imola quoted me the compressor at $314 and install at $220 which I thought was really good as long as I could get it there...of course I need to add drier and valve to list so that will bring up the cost but still really not bad. How much difficulty labor wise is swapping out the drier and valve?

Thanks,

John

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  • 2 weeks later...

I am going through compressor fail as we speak too.

From info I got, and some limited experience on other cars:

- this ac compressor is same for 4.5L engine (turbo or not) - 3.2L has different compressor

- both compressors for the cayenne do have a clutch that engages compressor when needed

- to do the job right yourself, get the right parts (ac compressor with clutch for your engine type, dryer which must be replaced if you ever brake the ac line circuit, install the parts, have the system flushed to ensure there is no metal/debris left in the lines if the compressor failed, ensure to check expansion valve to make sure not broken/replace if needed, replace the orings on lines going to the compressor, then pull vacuum on system to make sure there are no leaks, then put refrigerant into the system along with proper amount of oil for the compressor).

- would recommend checking serpentine belt and replacing if needed (good time while you are doing the ac stuff anyway down there). I bought mine for $50 for the car shipped.

- Drive away freezing your ballz off

I have the parts, now am contemplating whether to give the parts to shop for install/ready, or if I should install the parts and then let dealer do the flush and refill.

If they install parts they only warrant labor for 90 days. parts come with 1 yr warranty themselves.

If I do install, shop only warranties labor for 90 days.

Difference in price is if they do all, about 600 labor cost. If I do it all and they flush/refill, then 250. Already paid for refridgerant (they refilled then noticed compressor not engaging, then noticing busted clutch - had low pressure in it for a while and TX heat must have killed it).

Got my ac compressor with clutch (new-Denso), dryer, orings for $490 shipped total in case someone wonders.

Hmmmm, one though here though, should the pressure switch not deactivated the compressor?

Edited by ciaka
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The cracked compressor in this '04 Cayenne turbo is Nippon Denso 7SEU17C. When I was in a local general auto shop we looked up porsche replacement parts for that vehicle and it stated that the replace compressor is clutched for 4.5 and for the v6. I was in a suburban at the time... not the Cayenne. I am going to bring Cayenne into that shop and have him take a look at the compressor and decide if it is clutched or not. The tag on the compressor is the Nippon Denso 7SEU17C. ND Oil 8 R134a. McBit500 post shows it should not be clutched. Then we are back at the point of potentially seizing the pump while driving 250 miles to a porsche shop.

Managed to attach photo! The inch long crack to the left of the tag in the casing is the culpret. I will get a photo of the pump pully and post that too...later after I can pull off shrud and get a pic.

post-86237-0-81527000-1372394286_thumb.j

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