2005 B6 S4 A/C Compressor Issues

[JimmyBones]

Oh and in case it hasn't been covered in this thread, the lock carrier does not have to be removed to get the compressor... Service position is all you need.

Have you ever actually replaced an AC compressor on one of these cars? You would have to really stretch the lock carrier to get the AC compressor out. It is fun enough to wiggle the AC compressor out past the water pump with the lock carrier totally off.

[ProtoFly]

To those who have done their timing guides and tensioners, and have discharged their A/C:

When filling the system, how much PAG oil did you need to add, and how much R134? The Bentley manual isn't clear on what quantity should be added to a properly evacuated system.

[mrh12000]

i removed the whole front section when i pulled the compressor, and to make life easier to replace lower rad hose i acutally cut it off and found a piece of hose to use with regular hose clamps. i found it impossible to get the plastic fitting into the rad in the service position.
i could not actually get the compressor out without removing the water pump, and learned the hard way (twice cause im really stupid) that you can break the casting for the water pump drive shaft if you try put it on without setting that drive shaft into the pump (ie if leave the shaft in the engine it gets cocked going back in and snaps the casting).
i still need to know where the drive for the compressor is, but did get suggestion from local indy to keep an eye on and pull that shaft to lube it as they can shear the splines like mine.
i guess i will drive if without the shaft till i get the motivation (and a manual) on how to replace that drive sprocket or whatever it is.

[RPMtech147]

Ill get on elsa when
when i get back to work
And post a diagram

[vacsimile]

Have you ever actually replaced an AC compressor on one of these cars? You would have to really stretch the lock carrier to get the AC compressor out. It is fun enough to wiggle the AC compressor out past the water pump with the lock carrier totally off.

Yeah I did mine about 9 months ago, I didn't have any issues with it at all. IIRC I disconnected the upper radiator hose on the right side to keep the nipple from breaking.

[mrh12000]

that would be great, i understand its in back of the timing chain assemby?

[mrh12000]

Ill get on elsa when
when i get back to work
And post a diagram

Any luck?

[mrh12000]

So I did get the drive shaft and can see where it was galling just ahead of the splines, so stupid the drive splines strip instead of the shaft. The Indy shop guy says the preventative is to push the boot back and work some grease in there.

[RPMtech147]

To those who have done their timing guides and tensioners, and have discharged their A/C:

When filling the system, how much PAG oil did you need to add, and how much R134? The Bentley manual isn't clear on what quantity should be added to a properly evacuated system.

When you pull the motor there's no need to add oil because you shouldnt loose any. When replacing the compressor or any component I drain into a measuring cup and add the exact same amount + 1oz to compensate for the residual left inside the component. If youre flushing the con/evap cors you will need to add at least 1 ounce each...You need to use some kind of solvent to flush them and then use compressed air to blow it out. It need to be good and dry or the solvent will break down the system oil. Just the flush takes a couple hours.....I you don't spend 2 hours flushing an audi ac, you didnt flush it well enough.

[ProtoFly]

When you pull the motor there's no need to add oil because you shouldnt loose any. When replacing the compressor or any component I drain into a measuring cup and add the exact same amount + 1oz to compensate for the residual left inside the component. If youre flushing the con/evap cors you will need to add at least 1 ounce each...You need to use some kind of solvent to flush them and then use compressed air to blow it out. It need to be good and dry or the solvent will break down the system oil. Just the flush takes a couple hours.....I you don't spend 2 hours flushing an audi ac, you didnt flush it well enough.

Thanks. I'll note that I didn't drain the system, but rather had a shop do a recovery - you know, the 'proper' way, lol. As I recall, I didn't drain any oil from the system when I unbolted the lines at the compressor, so should be good.

Since the system was open for a while, I'm replacing the receiver dryer. Is there any oil in there? Or would I just drain that and replace with equivalent amount?

I almost don't want to take it to the same shop that discharged it, as they charged me quite a bit (>80 bucks). Tempted to buy a vacuum pump and gauges, which would be a little more, but then I'd always have them for service going forward.

[mrh12000]

Thanks. I'll note that I didn't drain the system, but rather had a shop do a recovery - you know, the 'proper' way, lol. As I recall, I didn't drain any oil from the system when I unbolted the lines at the compressor, so should be good.

Since the system was open for a while, I'm replacing the receiver dryer. Is there any oil in there? Or would I just drain that and replace with equivalent amount?

I almost don't want to take it to the same shop that discharged it, as they charged me quite a bit (>80 bucks). Tempted to buy a vacuum pump and gauges, which would be a little more, but then I'd always have them for service going forward.

Don't buy the air vac pump it needs more continual flow than your compressor probably wants to run at, and is super noisy with compressor running.

[Isaac N.]

Hello everyone, I believe I am about to do this. Now I have no idea on evacuation and refilling. A/C systems and pressures still mystify me for some reason, but would be be possible to change the compressor and drier and then take the car to a shop and have them flush and refill it? Or is that something that needs to be done while it's in pieces?
Given I wouldn't turn the air on from my garage to the shop to have them do that.

[JimmyBones]

You want to take the car to a shop and have them suck the refrigerant out, then do the work, and take it back to them to fill it back up. I would pay for a hour labor if that and no more.

[s4play]

found this thread since from a search and my whole saga started when one day my A/C was blowing cold, next day the ECON light won't shut off meaning no A/C :(

After fiddling with it to no success I took it to the Audi dealer and they stated:


Confirmed customer concerns. Recover and Vaccumed system and Refill. Test A/C and still not cooling.
Performed GFF Scan and Found high pressure sensor (open circuit / short circuit to B+ Intermittent)



Thus I went out and ordered the right part from Audi dealer and replaced it myself. My question is do I still need a VAG or dealer to reset something before my ECON button will turn off? It still stays lit and I'm not sure why - do I need to vacuum and refill the system again?


thanks for any help! This is quite frustrating :(

[My05S4]

It really doesn't matter where you buy AC compressor from because it's a direct drive. You'll have to take the front end off to get to AC compressor. I've checked on the prices for a compressor for my S4 and it's going from $800-$1300 for that particular AC compressor

[devilbones]

found this thread since from a search and my whole saga started when one day my A/C was blowing cold, next day the ECON light won't shut off meaning no A/C :(

After fiddling with it to no success I took it to the Audi dealer and they stated:


Confirmed customer concerns. Recover and Vaccumed system and Refill. Test A/C and still not cooling.
Performed GFF Scan and Found high pressure sensor (open circuit / short circuit to B+ Intermittent)



Thus I went out and ordered the right part from Audi dealer and replaced it myself. My question is do I still need a VAG or dealer to reset something before my ECON button will turn off? It still stays lit and I'm not sure why - do I need to vacuum and refill the system again?


thanks for any help! This is quite frustrating :(

Where is that located?

[kavitzy]

http://jhmotorsports.com/shop/catalo...h=21_56_61_247


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[JimmyBones]

Where is that located?

The AC high pressure switch is located on the right side of the AC condenser. If you have a B6 S4 then you can just pull the driver's/left side headlight and get it out easily. The B7 S4s require you to remove the front bumper to replace the sensor.

http://jhmotorsports.com/shop/catalo...h=21_56_61_247


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They have been selling AC compressors at that price for a while. I replaced my back in the Spring and it was the same price.

[devilbones]

The AC high pressure switch is located on the right side of the AC condenser. If you have a B6 S4 then you can just pull the driver's/left side headlight and get it out easily. The B7 S4s require you to remove the front bumper to replace the sensor.



They have been selling AC compressors at that price for a while. I replaced my back in the Spring and it was the same price.

Thanks. I guess I should take it to Audi of Chantilly to see if they can run the diagnostics before I get into this.

[JimmyBones]

Or you can drive a little farther East on 66 and I can take a look at it PM me if you would like me to look at it.

[viridia]

Our cars use the Denso 7SEU17C compressor, which is used in many other applications (though usually belt driven in other makes). I haven't found any glaring reason why you couldn't pick up a remanufactured 7SEU17C for $200 and swap the clutches from belt to shaft. Thoughts?

[Jake@JHM]

We got them at a great price as stated above

[evildsmr]

I know this is an old thread but seems to be the best one to post my situation to regarding A/C issues. So i have no cold air blowing at all. I have no DTC's for sensors or what not. I have a gauge only suitable for the low side connection and i put it on and measured ~41 lbs. I also connected said gauge and turned on the car and proceeded to activate the HVAC system and there was no fluctuation in the gauge, it stayed at the 41 lbs. mark. I then got under the car and the shaft and hub to the compressor seem to be turning together with no wobble or play at all.... I'm stumped.... Can anyone shed some light on this or point me in the right direction to go from here... Thanks!!

[JimmyBones]

I know this is an old thread but seems to be the best one to post my situation to regarding A/C issues. So i have no cold air blowing at all. I have no DTC's for sensors or what not. I have a gauge only suitable for the low side connection and i put it on and measured ~41 lbs. I also connected said gauge and turned on the car and proceeded to activate the HVAC system and there was no fluctuation in the gauge, it stayed at the 41 lbs. mark. I then got under the car and the shaft and hub to the compressor seem to be turning together with no wobble or play at all.... I'm stumped.... Can anyone shed some light on this or point me in the right direction to go from here... Thanks!!

I would say that you need a new AC compressor, receiver drier, and orifice tube.

Just to be sure though if you have a vagcom then you can check one more thing. Go into the 08 module and check measuring value block channel 1. What is the bar pressure reading for the AC system? If it is like 8 to 10 bar then you have refrigerant and the compressor is just not turning on.

These S4 AC compressors just suck and they fail like clockwork, sadly.

[evildsmr]

I would say that you need a new AC compressor, receiver drier, and orifice tube.

Just to be sure though if you have a vagcom then you can check one more thing. Go into the 08 module and check measuring value block channel 1. What is the bar pressure reading for the AC system? If it is like 8 to 10 bar then you have refrigerant and the compressor is just not turning on.

These S4 AC compressors just suck and they fail like clockwork, sadly.

My bar pressure is at 3 with the car on and compressor supposedly running. Still thinking compressor kaput?

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[snotrocket555]

Any tips on separating the two nuts on the shaft. A little too tight for me to use heat. Has anyone removed the shaft and compressor as one unit?

[tampas4]

Quick heads up Europa parts have the compressors on sale for $400.00 Bout to pop mine in.

[S4AvantB6]

Just had mine done, twice. First Compressor which was a Denso unit purchased from Rock Auto was a dud out of the box. Returned that one and bought the one from Europaparts.com. They shipped it 2 day for a reasonable charge and I got a free gift! Just make sure the system is totally flushed and you replace the receiver/drier/orifice tube. Love having A/C again!

[Alexztt]

Any tips on separating the two nuts on the shaft. A little too tight for me to use heat. Has anyone removed the shaft and compressor as one unit?

I believe that is what post #13 or #14 is talking about.

[keithwbloom]

I would say that you need a new AC compressor, receiver drier, and orifice tube.

Just to be sure though if you have a vagcom then you can check one more thing. Go into the 08 module and check measuring value block channel 1. What is the bar pressure reading for the AC system? If it is like 8 to 10 bar then you have refrigerant and the compressor is just not turning on.

These S4 AC compressors just suck and they fail like clockwork, sadly.

Pulling you back in on this thread Jimmy.

My A/C has petered out slowly over this summer. I just followed your guide above and measured 6 bar with system off, between 13 to 16 bar with system on. I have logs of the other measurement blocks in group 001. A/C Valve Current = 0, A/C Valve Duty Cycle = 0%, and High-pressure Signal % = 24.5% when system is off; Current ~ .652, Duty Cycle ~ 68 - 72%, High-pressure 42 - 44% when system on.

The air that blows is cooled, just not nearly as cooled as it should be. Seems like compressor is definitely running, you can feel the drain on the engine at idle when the A/C is switched on.

Coolant charge or likely compressor replacement? S4 has 117K miles.

Europa Parts has compressors for $400, the orifice tube for $30, the receiver/dryer is not listed. I can probably get from ECS or Audi direct.

[REVOofRustler]

I figured I'd bump this thread with some info from pulling my compressor just now.

I've had my car for a little over a year now, and it hasn't had AC since I've owned it. I had a shop try to recharge it, and they said it was leaking right out of the compressor. So finally I decided to take the plunge and replace my compressor. After I got the core support off, I sprayed some soapy water on the compressor and blew some compressed air into the line that would be connected to the condenser. Sure enough, it had a leak around almost the whole circumference of the compressor right around where the AC lines hook up to it. Leak spots are circled in green.




So I set out to pull it out. I hooked up an engine hoist and then I pulled the motor mount and the mounting brackets. It cleared up a good amount of room to work with, but I COULD NOT get the compressor unscrewed from the prop shaft. After a couple hours of struggling I finally decided to just undo the six allen bolts on the connector plate of the compressor. They all came out very easily. I took out the ones that I could easily get to, and then I cranked the motor very briefly with the fuel pump fuse pulled so that the prop shaft would spin and I could get to the next bolts.




I may try to get that plate off once my compressor shows up, but I don't really see why it wouldn't work to put it back together the same way. Sure sounds easier. Anyways, after I finagled the compressor out of it's too small home, I noticed that the compressor shaft was also broken.




So that's where I'm at now. I'm gonna try the Nissens compressor from JHM and see if saving the 200 bucks on the OEM one is worth it. I should hopefully have all the parts by the end of the week, along with AC manifold gauges, an AC flush kit, and a vacuum pump. I'm gonna have a lot of free time next week, so that's when it'll all go in.

[ImAudiHeree]

I figured I'd bump this thread with some info from pulling my compressor just now.

I've had my car for a little over a year now, and it hasn't had AC since I've owned it. I had a shop try to recharge it, and they said it was leaking right out of the compressor. So finally I decided to take the plunge and replace my compressor. After I got the core support off, I sprayed some soapy water on the compressor and blew some compressed air into the line that would be connected to the condenser. Sure enough, it had a leak around almost the whole circumference of the compressor right around where the AC lines hook up to it. Leak spots are circled in green.




So I set out to pull it out. I hooked up an engine hoist and then I pulled the motor mount and the mounting brackets. It cleared up a good amount of room to work with, but I COULD NOT get the compressor unscrewed from the prop shaft. After a couple hours of struggling I finally decided to just undo the six allen bolts on the connector plate of the compressor. They all came out very easily. I took out the ones that I could easily get to, and then I cranked the motor very briefly with the fuel pump fuse pulled so that the prop shaft would spin and I could get to the next bolts.




I may try to get that plate off once my compressor shows up, but I don't really see why it wouldn't work to put it back together the same way. Sure sounds easier. Anyways, after I finagled the compressor out of it's too small home, I noticed that the compressor shaft was also broken.




So that's where I'm at now. I'm gonna try the Nissens compressor from JHM and see if saving the 200 bucks on the OEM one is worth it. I should hopefully have all the parts by the end of the week, along with AC manifold gauges, an AC flush kit, and a vacuum pump. I'm gonna have a lot of free time next week, so that's when it'll all go in.

pstttt, https://www.fcpeuro.com/products/aud...or-4f0260805ah . Your welcome.

[924Carrera]

pstttt, https://www.fcpeuro.com/products/aud...or-4f0260805ah . Your welcome.

Yeah I got mine through FCP too. My compressor shaft was also seized in place like that, so I pulled it out with the compressor and ended up buying a new shaft as well.

[REVOofRustler]

The compressor I ordered is one made in Denmark. I read somewhere that those ones were a bit better quality than the chinese ones. I guess we'll find out!

[ridenickel9]

I am currently debating doing this... I have all Nissen parts quoted. Compressor, dryer, AC line o ring, orfice tube, oil, pressure safety switch, evaporator, condenser. My system is bone dry as it all leaked out.. so I assume I only need to flush the lines - add oil to compressor- spin 10 times - put it together, drive to midas for evacuation & fill? Isn't the evacuation going to remove the oil ??

I am trying to ball park the steps... knowing that this describes a perfect scenario. I'm pretty sure this is going to be a trip.

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[924Carrera]

I am currently debating doing this... I have all Nissen parts quoted. Compressor, dryer, AC line o ring, orfice tube, oil, pressure safety switch, evaporator, condenser. My system is bone dry as it all leaked out.. so I assume I only need to flush the lines - add oil to compressor- spin 10 times - put it together, drive to midas for evacuation & fill? Isn't the evacuation going to remove the oil ??

I am trying to ball park the steps... knowing that this describes a perfect scenario. I'm pretty sure this is going to be a trip.

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The Nissens condensor is not a good choice, as I personally learned when I bought one and found that it is missing all the mounting points for the power steering cooler. If you have an aftermarket cooler setup, then it's fine, but if you're stock, OEM is your best condensor option.

Replacing the evaporator is probably not necessary unless you had a leak from it, which isn't common (though it is possible). Replacing it is a massive pain that involves pulling the dash, so I'd advise against it unless you have good reason.

The Nissens compressor that I got came with the correct amount and type (PAG 46) of oil, but if you're not sure you can always drain and refill it.

Flushing the lines is definitely a very important step, so you're on the right track there. Shoddy shops will skip this step to save time and the result is a system with metal shavings in it that can quickly wreck a new compressor. If you opt to leave the evaporator alone as I did, make sure to flush through it in the opposite direction of refrigerant flow so that you don't wash any stray fragments into the evaporator, where they may become lodged and then resurface later.

Evacuation doesn't remove the oil. Freon is much lighter than oil and therefore easily sucked into the machine. For this same reason, you must ensure that your lines are thoroughly dried out after flushing, because the evacuation won't remove any flush liquid either, and this will immediately contaminate your receiver/dryer.

Driving the car without refrigerant is not good on the compressor. Having the oil in the system is obviously most important, but the freon is what circulates the oil around and without it, the compressor isn't going to get proper lubrication. As long as the Midas is very close by, it should be OK, but otherwise towing it is safer.

The steps I followed on my procedure were as follows:

Drain coolant and remove lock carrier. Support engine and remove motor mount and bracket. Unbolt compressor and find that it is seized to the shaft and won't come out. Remove water pump (and discover seals that have to be replaced as a result, therefore stalling my process) to get the necessary clearance. Install new compressor and shaft, packing splines with grease where they engage the drive unit on the engine. Make sure the sleeves/bushings that go in the compressor mounting bracket are in place, as they may end up sticking to the old compressor.

Remove old orifice tube. Flush for hours. I had a crappy flush machine and it turned into a giant pain. Swap condensor over (easy enough to figure out). Replace orifice tube. Reassemble lines, using a bit of mineral oil to lubricate O-rings as they are installed. Replace receiver/dryer; DO NOT torque bolts on its fittings to the spec listed in Bentley or Mitchell guides, which is far in excess for the size of bolt. I didn't think about it as I was doing it and snapped one off. Looking up general bolt torque guidelines later, I realized the listed spec was something like 2x what it should have been. Simply tighten until snug.

At this point I used an AC machine to evac and recharge, but since you do not have that luxury, you'll take it to a shop for that.

The Bentley guide isn't always the most helpful, but in this case it was actually quite thorough about the instructions for the compressor, so that was helpful.

[ridenickel9]

924Carrera thanks a lot!! That's awesome info and a great help to get going. I also just read a write up about flushing from:

http://www.teamec.be/cms_files/Flush...eaning(EN).pdf

This was very good as well and makes me think I need to bring all the separate parts somewhere and have them flushed with a machine. I am fairly good with this car fixing mechanically , but AC I have very little knowledge. I don't think my version of flushing was going to cut it!


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[924Carrera]

924Carrera thanks a lot!! That's awesome info and a great help to get going. I also just read a write up about flushing from:

http://www.teamec.be/cms_files/Flush...eaning(EN).pdf

This was very good as well and makes me think I need to bring all the separate parts somewhere and have them flushed with a machine. I am fairly good with this car fixing mechanically , but AC I have very little knowledge. I don't think my version of flushing was going to cut it!


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That's a good and informative document. However, unless you don't have access to an air compressor, you don't need to take them to a shop. You can get some cheap open-loop flush systems that connect to compressed air, for a reasonable price even on places like Amazon. Also, note in step 4 (the first one, looks like they accidentally repeated the number 4) they mention only removing and flushing the evaporator in cases of "extreme contamination." You can do as you please, but to avoid the major hassle of removing the evaporator (at which point I would just replace it anyway), I'd leave it in the car and just flush from the end of the line coming out of the evaporator, and let the flush flow through and drain out the end of the line going into the evaporator.

Edit: I also edited my above post to say to use mineral oil instead of PAG when lubricating the O-rings. That's actually what I did, but I spaced out when I was typing it and reading through that document reminded me. PAG oil is hygroscopic and you don't want to attract moisture to the sealed connections.

[ridenickel9]

10-4 924! Thanks again for advising and taking a minute to review my link. I am now much better armed than I was a few hours ago. Having AC again after 2 years will be awesome.

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[REVOofRustler]

........Unbolt compressor and find that it is seized to the shaft and won't come out. Remove water pump (and discover seals that have to be replaced as a result, therefore stalling my process) to get the necessary clearance. Install new compressor and shaft, packing splines with grease where they engage the drive unit on the engine. Make sure the sleeves/bushings that go in the compressor mounting bracket are in place, as they may end up sticking to the old compressor........

Will the shaft that drives the compressor slide out of the back of the motor? Mine moves in and out a bit, but I never got it to slide all the way out. That would sure make it a whole lot easier to undo that connection at the compressor.

Anyways, other than my orifice tube which should be here hopefully Wednesday, I've got all my parts (and some new tools) piled up for reassembly!