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Hi everyone!

I know you may all know by now the location of the a/c relay in you cayenne, and as easy as it may sound, I cant find it anywhere. I am usiming it is located in the e-box, hoever, there are a few there and I cant find any directions to which one from those it is.

Any suggestions?

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Hi everyone!

I know you may all know by now the location of the a/c relay in you cayenne, and as easy as it may sound, I cant find it anywhere. I am usiming it is located in the e-box, hoever, there are a few there and I cant find any directions to which one from those it is.

Any suggestions?

 

Welcome to RennTech :welcome:

 

When asking questions like this, it is always good to include the year and model and they are not always the same.

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Im sorry. I am new to forums.

I run a 2004 cayenne 4.5L turbo with 85k miles on it. The ac compressor doesnt engage. I notices the clutch was someone eroded and bent, almost cracked. I made that piece good again and when tried, the car melted the plastic in the clutch as if the compressor would not move.

I intention is to find out if it is the relay that is not working, before purchasing an expensive compressor. Thanks

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Im sorry. I am new to forums.

I run a 2004 cayenne 4.5L turbo with 85k miles on it. The ac compressor doesnt engage. I notices the clutch was someone eroded and bent, almost cracked. I made that piece good again and when tried, the car melted the plastic in the clutch as if the compressor would not move.

I intention is to find out if it is the relay that is not working, before purchasing an expensive compressor. Thanks

 

Should be R3:

 

post-1-022928600%201285000818.png

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Thank you JFP! Very useful. Im gonna look into that and see if current is going through, otherwise, I will have to look into a new compressor I guess.

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You should be able to put a socket on the compressor/clutch shaft and see if it spins with only a little effort. And without the belt on you should be able to spin the clutch pulley easily. Put 12v to the A/C clutch wire and see if you hear the clutch click as it engages. Normally on filling (everything in good condition) you would fill with liquid Freon to a vacuumed system. Filling with gas on a running system requires you to bypass the low-pressure switch or the clutch won't engage as the low-pressure switch senses a low-pressure condition and keeps the clutch from engaging. Factory procedure though is to vacuum the system and fill with a pre-determined amount of liquid freon (the best way to do it). The amount varies from year to year and whether you have dual A/C or single system.

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Hello hahnmgh63,

Thank you for your explanation. Quite technical. I noticed the metal cover on the clutch was bent outwards, the clutch would spin with the compressor but not its cover, which is the piece that engages the system. So I made that part to its regular shape so it would fit and engage into the compressor. Put the belt back on and ran the car. When I did, the car started hard and the rpm suddelty jumped high then down to normal. I lot of smoke came out. I checked and noticed that the black metal piece I fixed and engages, did not move but the bigger gear did move with the engine and belt, melting down the plastic inside it, that has the same shape as the black outter cover. My explanation is, once I made the engaged (supposing it was enganged) part or clutch move with the belt, it didnt and so the friction is breaking the inner rubber part. Maybe the compressor does not work thus the friction when engaged. I dont know. Am I missing something?

I did not know about vaccuming the gas. You mean extracting the gas out of the system completely until there is no more pressure or gas in it? I did that before but didnt help. Are we talking about the same vaccuming? I also gave 12v to the compressor but nothing happened. All very confusing.

Edited by Bichito

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Hello hahnmgh63,

Thank you for your explanation. Quite technical. I noticed the metal cover on the clutch was bent outwards, the clutch would spin with the compressor but not its cover, which is the piece that engages the system. So I made that part to its regular shape so it would fit and engage into the compressor. Put the belt back on and ran the car. When I did, the car started hard and the rpm suddelty jumped high then down to normal. I lot of smoke came out. I checked and noticed that the black metal piece I fixed and engages, did not move but the bigger gear did move with the engine and belt, melting down the plastic inside it, that has the same shape as the black outter cover. My explanation is, once I made the engaged (supposing it was enganged) part or clutch move with the belt, it didnt and so the friction is breaking the inner rubber part. Maybe the compressor does not work thus the friction when engaged. I dont know. Am I missing something?

I did not know about vaccuming the gas. You mean extracting the gas out of the system completely until there is no more pressure or gas in it? I did that before but didnt help. Are we talking about the same vaccuming? I also gave 12v to the compressor but nothing happened. All very confusing.

 

Either the bearing in the front of the compressor, or the compressor clutch bearing may be seized.  In any case, I would suggest taking the car to someone with the necessary equipment to diagnose and repair the system.

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Thanks JFP. I think I may be better off just getting the compressor replaced. I was looking for a DIY kind of situation, and although I am sure I can open it a have a look into it, maybe even fix it (or at least know for sure why it is not moving as soon as I engage it, it may not be worth the time and effort giving it has got 84k miles on it. Right? 

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@JFP in PA would you happen to have a diagram to go with that list?  I have a 2006 CTT that has no cold A/C.  Everything checked out at the A/C shop but they said there is no voltage going to the compressor.  This tells me there is a fuse or relay (perhaps) that has gone out.  I have an aftermarket part number for an 'A/C Control Relay' for this car but no porsche number and no location.  I'd like to try swapping out another relay to test.  If you have a diagram that would sure help.  I haven't seen a diagram with the same designations that are shown in the list you provided above.

Screen Shot 2017-06-02 at 5.10.49 PM.png

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I recently successfully self-diagnosed and repaired the A/C on my Cayenne. Total cost for parts and refrigerant ~$65. Vent temps went from 17 C before the fix to 4 C in ~24 C / 75 F ambient temps and high humidity. I will post details on the fix and the way to diagnose this particular problem (and other HVAC issues) in a new thread.

 

Anyways, one thing I discovered is that there is a lot of incorrect information out there regarding the HVAC system on these cars. One of the more pertinent items: The Cayenne uses a variable displacement compressor with an electronic compressor control valve for modulating the mass flow of refrigerant through the compressor. There is no compressor clutch, so to speak. This is not like the old compressors that we are all familiar with that use an electric clutch to cycle the compressor ON/OFF.  Please gently slap anyone who talks about an electric clutch on the Cayenne compressor. If you are in doubt, just do a google search for "Cayenne AC compressor" and look at the pictures. There is only a single electrical connector and it routes to the back of the compressor; this is the compressor control valve.

 

The HVAC control unit adjusts the refrigerant flow to meet the required demands. Instead of cycling a clutch on and off, a swashplate inside the compressor adjust the stroke of the compressor pistons to realize the specified refrigerant mass flow. No more ON/OFF cycling, just nice consistent cooling--in theory, at least (and when everything works).

 

Fuse 11 that Loren mentions powers the compressor control valve. The negative lead goes to the HVAC control unit. The valve is driven by a PWM signal, likely current controlled.

 

To the OP (Bichito): Sorry to say it, but your compressor is toast. The part that you are referring to as a clutch is actually a sacrificial break-away mechanism. The idea is that if the compressor locks up then this part will break in two and allow the pulley to spin so that your other accessories are still driven. I can think of no other scenario for your situation other than a catastrophic failure of the compressor. If you are lucky, then the compressor didn't spit it's guts throughout your refrigerant system. Either way, you will need a new compressor (and drier, at a minimum) and a very thorough cleaning of the refrigerant system (get this part wrong and you may be doing the whole job over again). Sorry...

 

@neoplanet: Your problem may be far less serious but we need more information. You wrote that the A/C shop said that everything checked out OK. What does this mean? I'm assuming that this at least means they did a visual inspection of the A/C compressor and did not see anything obviously wrong (like what Bichito found). Did they give you any pressure numbers? Do you get any cooling whatsoever? You wrote that they said there was no voltage going to the compressor. I'm not convinced they checked this correctly. First of all, hopefully they realized that the connector they were looking at was for the compressor control valve (not a clutch, as it doesn't have one). According to the manual that I have, +12 V should be on the red/white wire. Now, if they disconnected the connector and attempted to check the voltage across both leads then they would likely run into a problem because 1) the valve is controlled by a PWM signal (you need an oscilloscope, not a multimeter) and 2) the control valve is most likely current controlled: if you take the valve (which is low impedance) out of the circuit then the computer will recognize this as a problem and probably will not drive the line low. I would totally expect them to find 0 V if they tested things this way. You can test the +12V wire by connecting one lead of a voltmeter to the red/white wire and the other lead to anywhere on the car that is grounded. To properly test that the electronic signal to the valve, you need to keep the valve in circuit and probe across both wires with an oscilloscope. Frankly, I wouldn't waste my time doing this at the moment. First thing I would do is get some pressure readings. If your high side pressure is OK then you can forget about the electrical checks on the control valve. Once I know your pressure readings I can make a suggestion as to what I would check next.

 

Brett

 

p.s. To address the original question, there is no A/C relay on the Cayenne and therefore no "A/C relay location". :) Edit for clarification: I should have said that there is no "A/C compressor clutch relay". I also just noticed that this thread was a year old. Oops! 

Edited by Brett968
  • Upvote 3

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2 hours ago, Brett968 said:

Please gently slap anyone who talks about an electric clutch on the Cayenne compressor.

Ha ha ha ha haaaa

  • Upvote 1

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Thanks @Brett968.  First let me say you just blew my mind :thumbup: with your generosity and your knowledge of this thing!  So, thanks for delivering some truth and clarity.  Ok, no clutch!  Sounds like a cool way to do A/C.  Let's see now what I can answer...

 

They did the visual inspection and didn't find anything obviously wrong.  I did measure the pressure on the low side at 125 psi with everything turned on at the console.  I know it's supposed to be much lower but they said that is not unusual if the compressor is not running.  I don't remember their numbers but they didn't seem inconsistent with mine so no flag in my memory.   High side was similar to low side pressure.  Pretty sure they said it had refrigerant in there.  I don't know how they can tell.  They seem like a decent shop that has been here for 60 years.  They just said it must be something electronic that they don't have the equipment to diagnose.  I figure since they used the words "no voltage" that they weren't expecting a PWM signal so good point there!  

 

If I'm not imagining things, I think the temp goes up and down very slightly on a cycle of a few seconds but it is generally warm.  Never feels like cooling.  Never drops any condensation on the ground.  It went from dripping a LOT to dripping not at all.  I will mention, just in case it is relevant, that the interior fan went out a while back and I replaced that about a week before the cooling quit cooling.

Edited by neoplanet

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OK, I am going to assume then that the compressor is being driven (pulley isn't freewheeling around the compressor shaft like the OPs).

 

A Durametric tool would be really useful at this point. We would like to know whether the climate computer is requesting refrigerant flow or if it indicates some fault elsewhere (e.g. bad pressure switch, etc.). Do you have access to a Durametric tool? Even just a basic fault code reading of the HVAC computer with any compatible OBDII tool would be better than nothing.

 

If the climate computer doesn't point to any other apparent problems then you may want to look at the compressor control valve. This is the part that fixed my car. I suspect a number of other Cayennes are plagued with weak or inoperative A/C due to this valve malfunctioning. You can source the valve from a few places online. Note that there are several different versions of the valve for Nippon 7SEU17 compressors (the type in the Cayenne) depending on application. You need the one with the pigtail connector. I know that the Gogoal ECV03C is one option that works for these cars and you can get it for $42. To replace the valve, you need to remove the refrigerant, replace the valve on the compressor, change the drier and then recharge the system. The valve is held into the compressor with an internal snap ring and is very easy to replace. Do not attempt to remove the snap ring while the system is pressurized or the valve could become a high-speed projectile! The valve can be replaced with the compressor in the car but I found it was easiest to remove the compressor (only takes 15 minutes). A good shop should be able to do the whole job in a few hours tops. (BTW, the pigtail on the replacement valve was 0.5cm shorter than the original. I had to flip a wire retaining bracket around 180 degrees to make it reach.)

New and old compressor control valve

Compressor control valve (old) -- location on compressorHaving said that, it is quite possible that something else is wrong. I would try to get all the diagnostic information I could before throwing any parts at the problem.

 

Brett

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I'll check the codes again. I have android ODB2. No durametric. I did check before and only had an issue to do with secondary air injection. But I think the A/C was working then. I'll check and reply. 

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Make sure that your OBD2 tool is specifically querying the HVAC computer for fault codes and not just the engine computer, etc.

  • Upvote 1

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I have the "Torque" app.  It doesn't list any A/C related codes in the custom area.  The fault codes displaying are only as before (secondary air injection) which is another story.  The A/C PID could be entered but it is asking for hexadecimal "AA BB" type code input to be able to add custom and check them.  Any idea where I can look this up or perhaps you have the hex code?  From my looking around it appears there are codes for A/C Pressure Switch and other related A/C items but I would need to enter the hex codes.  Any clues you can provide may shed some light.

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You will need a Porsche specific diagnostic tool to read most anything other than engine fault codes.

Durmatetric is the most popular.

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I'm afraid Loren is right. Do you know anyone that has vagcom? That should also work in this situation due to chassis sharing with the Touareg.

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No, I don't know anyone with the vagcom.  Guess I'm not social enough!  Good try though, thx.  Seems I should be able to read anything if I have the right code & setup info for the specific thing I'm looking for on the specific vehicle.  Looking into it.  I'm sure the info is out there.  OH!  I just remembered, I ordered the FSM the other day.  Better go download it and see what's in there.

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The FSM of course just tells you how to troubleshoot using the Porsche tester. No "under the hood" commands for the bus. I gave up on trying to find commands for my Torque tool.  I'll have a new code reader, Porsche iCarsoft i960, in a few days.  Says it includes the Air Conditioning control.  Hope it works!

Edited by neoplanet

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The code reader gave 0898 which is air conditioning compressor not engaged... something like that.   Funny story... I replaced a valve cover gasket a couple of months ago.  Some of you may know that wire that goes over the left valve cover.  I've learned it goes to the A/C compressor.  I had read another post where someone decided to cut and splice that wire rather than disconnect it from wherever down in there they could see it went at the time.  I :blink: for some reason thought that sounded like a good idea!  So, I've discovered the splice job I did was faulty.  I soldered and shrink wrapped it and all's good. Moral of the story: If you don't have time to do it right, when will you have time to do it over again?!  Thanks for all your help loren, guys.  Sure appreciate it!  It's good to be on here and I'll see what contribution I can make. 

Edited by neoplanet

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On 2017-6-8 at 2:19 AM, Brett968 said:

OK, I am going to assume then that the compressor is being driven (pulley isn't freewheeling around the compressor shaft like the OPs).

 

A Durametric tool would be really useful at this point. We would like to know whether the climate computer is requesting refrigerant flow or if it indicates some fault elsewhere (e.g. bad pressure switch, etc.). Do you have access to a Durametric tool? Even just a basic fault code reading of the HVAC computer with any compatible OBDII tool would be better than nothing.

 

If the climate computer doesn't point to any other apparent problems then you may want to look at the compressor control valve. This is the part that fixed my car. I suspect a number of other Cayennes are plagued with weak or inoperative A/C due to this valve malfunctioning. You can source the valve from a few places online. Note that there are several different versions of the valve for Nippon 7SEU17 compressors (the type in the Cayenne) depending on application. You need the one with the pigtail connector. I know that the Gogoal ECV03C is one option that works for these cars and you can get it for $42. To replace the valve, you need to remove the refrigerant, replace the valve on the compressor, change the drier and then recharge the system. The valve is held into the compressor with an internal snap ring and is very easy to replace. Do not attempt to remove the snap ring while the system is pressurized or the valve could become a high-speed projectile! The valve can be replaced with the compressor in the car but I found it was easiest to remove the compressor (only takes 15 minutes). A good shop should be able to do the whole job in a few hours tops. (BTW, the pigtail on the replacement valve was 0.5cm shorter than the original. I had to flip a wire retaining bracket around 180 degrees to make it reach.)

New and old compressor control valve

Compressor control valve (old) -- location on compressorHaving said that, it is quite possible that something else is wrong. I would try to get all the diagnostic information I could before throwing any parts at the problem.

 

Brett

Hi Brett, some good knowledge in this thread, was hoping you might be able to offer some advice for me pls. 

Fyi I did start a new thread on this....

I got a ctt 2006 with 4 zone AC, the AC was working but never was great, after being in the gagrage and coming out and back in again the AC stopped working, no idea what the shop did but another garage only pulled 170grams from the system and then wasn't able to regas it, he said the low side was blocked. I replaced both high and low side AC service valvea as they was damaged and the vaccum and regas 1100grams went well. But the AC won't blow cool at all, in fact it hot ambient air. 

Ac compressor is on and climate controller seems to be working just fine. No codes, output tests all passed, vagcom vcds all checks out ok, compressor amps 0.8 @ 84% load.

Test Gauges say 100psi on low side (too high)  and 200psi on high side(a bit low). 

The garage tech said expansion valve is blocked he thinks. I'm reading also the compressor control valve could be at fault. 

If the CCV was not working wouldn't there be no real increase in high side pressure compared to the low side? 

Any help and advice appreciated. Also struggling to determine which CCV fits this compressor there seem to be a few variations. 

Thanks 

IMG_20170713_1856177.jpg

IMG_20170713_1900110.jpg

IMG_20170714_1711113.jpg

IMG_20170714_1738473.jpg

Edited by lewisweller

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