Would a Bad AC Compressor Cause a AC Freon Leak?

[Audibellybutton]

Making this post hoping anyone experienced with AC can chime in.

My ac stopped working out of nowhere, its leaking pressure pretty quickly from the low side. All ac electronics are good and when I Check the AC compressor shutoff condition in VCDS it says "low pressure event" basically confirming the compressor wont come on due to a leak.

I have been unable to find the leak with UV dye and my only clue is a faint hissing noise under driver side HPFP near where the compressor is. With a leak this big you would think the dye would be easily visible somewhere but nope, I can't see it anywhere

Since I couldnt find the leak I took it to an AC shop for a diagnostic. I watch them fumble around and be puzzled about the leak for about 30 mins and then ultimately they told me its a bad compressor.

I'm obviously reluctant about this because I have not found anyone who has had the same issue and the compressor is an extensive job to change. I also have the dealership repair manual that states my symptoms point to a leak that needs to be fixed, and not the compressor.

Of course it is possible it is the compressor, I just want to hear some opinions if anyone else has experienced this.

To my understanding a bad compressor would still hold pressure but fail to engage. I could be wrong about that though

A new compressor is around $3500. I may be at the end of the road with this car. $3500+ on something that isn't giving me no horses just might be where I draw the line.


the car is a 2013 S6 with 89k miles.

[Burkeomatic]

Making this post hoping anyone experienced with AC can chime in.

My ac stopped working out of nowhere, its leaking pressure pretty quickly from the low side. All ac electronics are good and when I Check the AC compressor shutoff condition in VCDS it says "low pressure event" basically confirming the compressor wont come on due to a leak.

I have been unable to find the leak with UV dye and my only clue is a faint hissing noise under driver side HPFP near where the compressor is. With a leak this big you would think the dye would be easily visible somewhere but nope, I can't see it anywhere

Since I couldnt find the leak I took it to an AC shop for a diagnostic. I watch them fumble around and be puzzled about the leak for about 30 mins and then ultimately they told me its a bad compressor.

I'm obviously reluctant about this because I have not found anyone who has had the same issue and the compressor is an extensive job to change. I also have the dealership repair manual that states my symptoms point to a leak that needs to be fixed, and not the compressor.

Of course it is possible it is the compressor, I just want to hear some opinions if anyone else has experienced this.

To my understanding a bad compressor would still hold pressure but fail to engage. I could be wrong about that though

A new compressor is around $3500. I may be at the end of the road with this car. $3500+ on something that isn't giving me no horses just might be where I draw the line.


the car is a 2013 S6 with 89k miles.

In my years before joining the military I was a Mazda tech, until about 2009 to be precise. With that being said, 99 percent of the time when compressors fail, it is pretty freaking obvious, and they usually lock up and make some awful sounds before they go.

The system really needs to be vacuumed out and pressure tested. Yeah, you can get results with chemical sniffers, and the dye works most of the time, but fact is, you lost refrigerant, and the compressor won't even kick over if the pressure is too low.

Also, have you checked the evaporator and the hoses going to that real well. Those bad boys can be tricky to find up in there. I haven't even looked at that area on our cars, never needed to, but lots of times that can be the case. Have you smelled any refrigerant when you drive.

[Audibellybutton]

In my years before joining the military I was a Mazda tech, until about 2009 to be precise. With that being said, 99 percent of the time when compressors fail, it is pretty freaking obvious, and they usually lock up and make some awful sounds before they go.

The system really needs to be vacuumed out and pressure tested. Yeah, you can get results with chemical sniffers, and the dye works most of the time, but fact is, you lost refrigerant, and the compressor won't even kick over if the pressure is too low.

Also, have you checked the evaporator and the hoses going to that real well. Those bad boys can be tricky to find up in there. I haven't even looked at that area on our cars, never needed to, but lots of times that can be the case. Have you smelled any refrigerant when you drive.

Exactly it seems AC issues are very rare on this platform so when it happens theres not many examples to go off of. ive checked the visible lines thoroughly but now I think I'll be pulling the bumper to see what else I can access. Even the compressor is not easily visible on these cars so if there is a leak in a connection near the compressor I'll need to do some tear down anyways

[Audibellybutton]

In my years before joining the military I was a Mazda tech, until about 2009 to be precise. With that being said, 99 percent of the time when compressors fail, it is pretty freaking obvious, and they usually lock up and make some awful sounds before they go.

The system really needs to be vacuumed out and pressure tested. Yeah, you can get results with chemical sniffers, and the dye works most of the time, but fact is, you lost refrigerant, and the compressor won't even kick over if the pressure is too low.

Also, have you checked the evaporator and the hoses going to that real well. Those bad boys can be tricky to find up in there. I haven't even looked at that area on our cars, never needed to, but lots of times that can be the case. Have you smelled any refrigerant when you drive.

my bad just saw your other question, I havent smelled any freon threw the vents, and didnt see any uv dye on the inside of them

[Botbasher]

You could simply have popped an o-ring on the fittings at the compressor. Give you all the same indicators as a bad compressor but "easily" repairable.

Dye is a helpful tool, but not a complete diagnostic. You need a leak that will carry oil out of the system and sometimes they simply don't due to orientation.

I'm of the same mind as Burk... when compressors go, they typically go spectacularly, but sometimes it's just a flaw in a fitting that fails.

I know it's a PITA, but I'd pull the bumper and poke around a little at the compressor as best you can. Get a slightly better look at all the lines and especially the fittings at the compressor if you can. If you know anyone with a vacuum pump, you can get a Harbor Freight adapter and pull a vacuum on it. Listen for the "leak" and follow it in.

With the sudden failure, I bet it's a seal. Be a shame to let someone drop in a $1400 compressor if it's a $3 o-ring!

Good Luck!

KS

[Burkeomatic]

It takes 20 minutes to pull the front bumper, but follow the lines all the way up to the evaporator and check those well too. Also, I know it is hard to catch small residuals so when you are checking this it is in a perfectly dark room. Sometimes the uv dye isn't very "concentrated" and can be hard to spot, in addition to some other things that can kinda glow under UV light.

[Botbasher]

From what I'm seeing in the service manual, you should be able to get a "ok" look at the fittings from under the car. It looks like it's right above and slightly behind the water pump housing.

Not easy but I'd try that before pulling the front of the car.

Good Luck!

KS

AC.jpg

[Audibellybutton]

From what I'm seeing in the service manual, you should be able to get a "ok" look at the fittings from under the car. It looks like it's right above and slightly behind the water pump housing.

Not easy but I'd try that before pulling the front of the car.

Good Luck!

KS

AC.jpg

this is golden I was trying to find out where it was, only had a general idea. I just did my thermostat I shouldve took a peak when i was in there lol Ill see what i can see with the bumper off though.

and to Burk yeah i agree even dried up coolant stains glow in the light sometimes lol

Anyways yeah I had a brief lapse of judgement, AC guy got in my head lol. I love the S6. Screw $3500 for no ponies though. If it comes down to it ill buy a used compressor and slap it on or have a shop do it. It could be as simple as a seal though so it doesnt hurt to check the lines and confirm.

[hunter_killer]

Even if a compressor goes out, unless it explodes, it’ll just not engage the clutch and the pulley will still spin. Usually a seizes compressor won’t leak unless it somehow cracked the housing and by then you’d know where the leak is. I agree that the system needs to be evacuated, vacuum/ leaked checked, and then it should be pressurized with nitrogen. With the nitrogen you should be able to hear the leak and check the system over with soapy water to find any size leak, no matter how small. I never liked using dye to find leaks. We don’t use it at work as it takes too long most of the time to get through the system and find it’s way out to be seen.


Sent from the howitzer using Audizine Forum

[Burkeomatic]

Even if a compressor goes out, unless it explodes, it’ll just not engage the clutch and the pulley will still spin. Usually a seizes compressor won’t leak unless it somehow cracked the housing and by then you’d know where the leak is. I agree that the system needs to be evacuated, vacuum/ leaked checked, and then it should be pressurized with nitrogen. With the nitrogen you should be able to hear the leak and check the system over with soapy water to find any size leak, no matter how small. I never liked using dye to find leaks. We don’t use it at work as it takes too long most of the time to get through the system and find it’s way out to be seen.


Sent from the howitzer using Audizine Forum

Yeah, that is what I was getting at.

I also don't know how to inspect that area after it passes through to the driver side in to the evaporator core, if you would have to get at it through the top, if there is shielding there you could pull off, or if you have to pull one of those contorted lay on your back in the floor with your feet up in the air look at it under the dash things.

There is always the hillbilly auto repair method of load some more refrigerant and buttloads of leak dye in it and keep loading it in there until it finally shows itself. If it is a rapid enough leak, like a blown o-ring, which I hope for his sake that is all it is, then it would give more time for the leak dye to load up. Of course once you identify it you would want to vacuum the system to get whatever contaminants there is out.

[Audibellybutton]

Yeah, that is what I was getting at.

I also don't know how to inspect that area after it passes through to the driver side in to the evaporator core, if you would have to get at it through the top, if there is shielding there you could pull off, or if you have to pull one of those contorted lay on your back in the floor with your feet up in the air look at it under the dash things.

There is always the hillbilly auto repair method of load some more refrigerant and buttloads of leak dye in it and keep loading it in there until it finally shows itself. If it is a rapid enough leak, like a blown o-ring, which I hope for his sake that is all it is, then it would give more time for the leak dye to load up. Of course once you identify it you would want to vacuum the system to get whatever contaminants there is out.

for what its worth I just turned the fan on again and it does smelll funny, maybe freon/evaporator related.

@hunter I think ill rent a vacuum pump from AutoZone as well, I remember seeing that as one of the tools they loan out

[Burkeomatic]

for what its worth I just turned the fan on again and it does smelll funny, maybe freon/evaporator related.

@hunter I think ill rent a vacuum pump from AutoZone as well, I remember seeing that as one of the tools they loan out

Cool, freon has a distinct smell, I can't really explain it. Kind of like raisins mixed with must and alcohol, though not near as pungent. It is pleasant and nauseating all at the same time.