cfiiman

Hey guys,

I cross posted this on Renntech as well so I can reach the most people that can advise. So my compressor wouldn't kick on the other day and after trying everything I new to do and scanning with Durametrics and finding nothing I took it to my trusted Indy. He found no faults either and said his hunch was the compressor is plugged b/c of debris and that I needed a new one. He put his gauges on the system and when revving the car the high pressure side didn't move hardly at all and he said it should go way down and that as many as he has replaced he is sure. I trust him implicitly, he is a friend as well. With that said he is moving in a few weeks across the country and is backed up solid, he said he "might" be able to get me in but not to get my hopes up. He said I shouldn't hesitate to do the job and then just bring it to him to pull the vacuum and recharge the system. I always do all the work to all my cars, only the Cayenne has ever gone to him and it is only because I don't have the coding abilities so I am mechanically inclined. He said the AC system is straight forward to remove, but he wants the compressor, dryer/condenser, etc. all replaced because of the crud that shot out of the system through his gauges. He said once it is all out I would need to flush the lines with an assload of brake cleaner. I have a lift in my garage so I'm thinking I'm going to tackle this, not really because I want to but because I feel like there is a definite possibility he will not be able to get me in before he leaves and I don't trust the other hack shops I know of around here. My thought is, if nothing else I can do most of the job so he has time to help if needed, but if I wait that window closes as he is shutting down his shop and plans to be gone by March unfortuantely. Has anyone tackled this job that can give some advice/pointers? I'm trying to get my hands on a service manual now but all I can find is from ebay sellers, if someone else has, or could send me the pages pertaining to this it would be greatly appreciated. I plan on filming the whole thing so it can be a diy for anyone in the future, but any guidance before I start would really help put me more in a favorable mindset. I'm already a little ticked I just bought the car and have this problem to deal with Thanks for any help!

19psi

First off, when revved, the low side (suction) goes down and the high side goes up. If the system was restricted, the high side would be extremely high and the low side may be going into a vacuum.
Little pressure change can be a faulty compressor or simply a failed TXV.
He feels the need to replace the condenser but not the evaporator?
Brake cleaner for a flush? Lol! Any mechanic should have a few cans of proper flush, such as rx11, sitting on their shelf.

oldskewel

What year / model?

Also, more info on this part would help: "because of the crud that shot out of the system through his gauges"

Also also, if YOU are going to remove and replace all that stuff, and flush the system, then all HE is going to do is to vacuum it down and charge it with oil and refrigerant. That part that he is doing is pretty much the easiest part of the job, unless you're also relying on him to check that you did everything sufficiently well, etc.

cfiiman

Sorry 2004 CTT. By crud I mean blackish looking stains that came out with the freon. He let some pressure out into a paper towel and it looked wet obviously but with a taint of blackish color. I don't remember seeing any larger particulates or anything, just the blackish color mixed with the clear on the paper towel. I've just never worked on AC systems before, I understand how they work but never had a need to remove/repair one until now, and as luck would have it, it is on a CTT. Can someone explain why so much needs to be replaced vs. just flushing it all out? Just trying to learn.

Andy E.

I agree with the others. Either your Indy is rushing to get outta Dodge, or his knowledge of basic refrigeration principles has been compromised.

Without knowing your level of proficiency in servicing vehicular A/C systems, my recommendation would be to visit a real expert who can guide you towards the light of climatic comfort.

cfiiman

Mechanically I'm experienced (replaced clutches, built turbo systems, etc.). I've talked to an expert AC shop this afternoon who worked with me in the past on a custom turbo car I built who said if I wanted to do the mechanical work they will flush the system when I pull it apart and then pull the vacuum and recharge to the proper amount once I get it all buttoned back up. I feel confident pulling it all apart except for the expansion valve, it sits pretty low in the passenger side cowl by the DME, but looks doable to get out. The expert AC place said that the condenser/dryer and the valve should be replaced, but being that the evap is a PITA huge job and is small enough that it can be flushed successfully. Not sure how I should go, I feel like I can get the compressor, condenser/dryer and expansion valve out based on what I've looked at on the car, I'm just wondering about the flushing part.

deilenberger

It's possible what was in the expelled gas was burned oil from the compressor. The oil circulates through the system with the gas. The problem point can be the expansion valve - it has a small orifice that can get clogged when debris starts circulating in the system. It can sometimes be cleared if you reverse flush it with R134. An important point - oil has to be added when components are replaced or the system has been bled down. That's usually done by ounces. The fill of a system is done two ways - one is by weight of R134, the other is system pressures on an operating system. The factory service manual has several plots of the different system pressures vs temperatures, and based on if the system is a 2 zone or 4 zone system. I don't quite understand the need to replace the condenser or evaporator.. explain please.

cfiiman

Hi Deilenberger,

Both the Indy and the expert AC tech told me the same thing because I felt the same way you did so I asked. The reason I got was the orifices are so tiny and many in the condenser that it is highly unlikely to get it all out. He said the expansion valve's tolerances are similar in that they are so tight it is difficult to 100% clear any contamination. He said that most manufacturers require when replacing a compressor that the condenser and expansion valve almost always have to be replaced in order for them to warranty the parts. This makes sense to me and the expansion valve and condenser are the cheapest parts anyway. I'm trying to figure out the best way to tackle the removal. The expansion valve looks fairly easy to get to if I remove the wiper arm cover so I could start there. I"m trying to figure out how to get the car over to the AC place to flush the system once it is apart. The front bumper cover has to come off to remove the condenser which also seems straight forward. I'm wondering if I could just remove the compressor and fit the new compressor in place without hooking it up obviously so I can drive the car over to the a/c place to get flushed or if I would need to flat bed it over?

I got my borescope camera out and here are some photos of the expansion valve (I couldn't find any when searching so thought they might help someone in the future). The first one is the body, second one is where the lines coming from the condenser/drier bolt on and in between those lines are the 2 bolts that hold the valve onto the evap line. I scoped everywhere around the valve and these are the only two bolts and they are on the front of the valve which makes for easy removal when the wiper cover is off:

Valve Body:


AC Lines From Condenser:


Expansion Valve Bolts That Hold It On To The Evap Flanged Line:

deilenberger

I suspect you could fit the new compressor and condenser and expansion valve and just not connect the electrical connection for the compressor. It would be safe to drive that way since just the pulley on the compressor would be turning - the compressor wouldn't be (the pulley drives the compressor through an electromagnetic-clutch.) Once you get it there and hooked up to his machine to pull a vacuum on it - then flush it - it would then be safe to connect the compressor and finish the fill.

Andy E.

Regarding flushing of the entire refrigeration circuit, here's an informative article on the subject which may aid you: https://www.achrnews.com/articles/85...inated-systems

Even though this article pertains chiefly to commercial refrigeration systems, the basic procedure and tools are still the same. An important note to remember is that R-134a based air conditioning systems use a polyolester (POE) synthetic compressor oil. This oil is highly susceptible to humidity; being the number one enemy in standard refrigeration. In order to avoid contaminating the new compressor and oil, it would be preferable to isolate them by not immediately connecting the compressor to the lines when flushing the system. In addition, in order to prevent the oil from absorbing humidity, the compressor service and shipping flange caps should only be open as a last step; prior to making your final connections and vacuum evacuation.

Please post pics of the contaminants once you've completed the flushing procedure.

cfiiman

Hi guys,

Thanks for the guidance.

deilenberger - I agree with your post and that is the plan for the most part.

Andy - Thanks for the link.

I ordered all the parts, and will be dissembling when they come in. The AC shop today shot some of the refrigerant into a white rag and said it was definitely contaminated but he had seen a whole lot worse so I guess that is the only good news if any. He agreed with Indy that the blackish color was from the compressor internals. Hopefully I caught it early enough. He showed me how to flush the system thoroughly with ac flush solvents and to blow the compressed air through the system and let it dry, etc. I'll be doing this once myself and then letting him do it again as well before pulling vacuum and recharging. I figure the system is shot at this point anyway so I'll give it a go and gain the experience in this area of the Cayenne.

oldskewel

Good to hear. One thing I'm curious about is whether it would be best to do the flushing with:
1. all the old stuff still in place
2. all the old stuff (compressor, condenser, all the parts you'll be replacing) removed, but the new stuff not yet installed, to prevent contaminating the new parts during the flushing
3. all the new stuff installed
4. something else

I can see pro's and con's of all of the above, and I expect a pro would know exactly which one is best. What's the answer?

Andy E.

In an ideal and perfect world (one in which we do not live in), a complete disassembly of all parts involved followed by a full inspection and analysis. Lastly, a chemical flushing of each independent component and subsequent reassembly.
The labor costs alone to do this would be prohibitively expensive. However, as a DIY project, Absolutely!

cfiiman

Yes, the AC guy said to disassemble as much as I could, but some lines that can't be removed need to be flushed on the car or not at all. Hopefully areas like the condenser and expansion valve have caught the brunt of the bigger particles as those will be replaced. I'll do my best in terms of flushing the best I can and put it back together and hope for the best, about all I can do at this point.

Here is a pic of the system from my service manual, looks like I can break the line systems up into shorter segments for flushing and I don't see a lot of tight bends which is good I guess:

cfiiman

Does anyone know if you have to pull the bumper cover to get the condenser/dryer out? I only ask because the service manual doesn't mention it, only to remove the engine guard and lock carrier, which I'm not exactly sure what they are referring to, I'm thinking it must be something different then the under trays or is that it? I'm guessing the lock carrier is the radiator support but engine guard, anyone know what they are referring to? It makes no mention of the bumper cover, and after looking at a pic of one removed I'm not sure how it would help that much since the condenser is pulled straight up and out?