Air Conditioning Failed

[STA4]

I tried using the air conditioning for the first time yesterday and it only blew warm air even on "Lo" setting. It was Auto mode and the fans were blowing hard and A/C light was on. I checked the fuse (it was ok) and I do notice the RPMs rise slightly with the A/C on, so I think the refridgerant has leaked out.

Has anyone else had their A/C stop working? I'm still under warranty and hope that my TD1 status doesn't cause me any problems. Hoping that something wasn't damaged during the install of my HFC or something like that either... I also hope that this is an isolated incident and not something that will be an ongoing type maintenance issue over the years.

[wrclaguna]

Fits hook VCDS and check for errors, it may no longer factor in the system.

[fre2bpowerless]

Ok just try this, have the A/C on low and full speed. Neutral and rev the car a bit, see if it starts blowing cool air.

I had this issue last year in peak summer, revving it every morning used to (somehow) kickstart the a/c. Over a month or so, things just went back to normal. I figured it was an Audi thing :D

[STA4]

You had to rev the engine in neutral? I drove around for a bit to see if it would cool down, but eventually got tired of the warm air and shut it off.

[fre2bpowerless]

You had to rev the engine in neutral? I drove around for a bit to see if it would cool down, but eventually got tired of the warm air and shut it off.

I know it sounds stupid but yes rev in neutral.

[Greg Nelson]

Try setting your climate control to 'auto' . Mine had been on 'recirculating' last month when it warmed up enough to go to AC, turning temperature lower did not activate AC. Switching to 'auto' did the trick.
BTW I have dual zone.
Cheers

[jfo]

Sorry if this is an obvious comment , but what temp did you have it set at? It would need to be below the current cabin temp to blow cool air. Even with A/C on , it will still heat if the temp setting calls for it.

[STA4]

The temperature was 27 celsius (80 something F). HVAC was set to:

Auto (everything)
"Lo" temp
A/C light on
Recirculate off

Based on lack of responses, I assume that this is a rare issue...which is a good thing.

[Greg Nelson]

The temperature was 80 something F

Seriously hot F. temperature.
Perhaps explains why neither Montreal nor Toronto made it to NHL playoffs this year - skates work best on ice, not slush/mush.
Cheers

[martian421]

I'm also running into issues with my '09 B8. The A/C had consistantly been good for the past 4 years. Upon turning on the system this weekend (we had a 70 degree+ weekend here in NYC) i was only able to get warm air out of the a/c unit.

i put the temperature at 60 degrees (even "LO" at one point) and still only warm air. It is normal that refrigerant needs to be refilled on a car my A4 (which is only 4 years old) - i guess, it potentially would need to be if i kept the AC blasting on hot days - which i recall doing since i drove around with my newborn last year...

[jfo]

I'm also running into issues with my '09 B8. The A/C had consistantly been good for the past 4 years. Upon turning on the system this weekend (we had a 70 degree+ weekend here in NYC) i was only able to get warm air out of the a/c unit.

i put the temperature at 60 degrees (even "LO" at one point) and still only warm air. It is normal that refrigerant needs to be refilled on a car my A4 (which is only 4 years old) - i guess, it potentially would need to be if i kept the AC blasting on hot days - which i recall doing since i drove around with my newborn last year...

Refilling the refrigerant isn't "normal". Extensive use of the AC has nothing to do with the disappearing refrigerant. It just keeps recirculating in a closed system and does not get used up unless there's a leak. A shop will add a UV sensitive dye and then check for signs of leakage. at joints, etc.

[dscline]

Automotive AC systems aren't completely closed like a home system is... there are seals such as at the shaft of the compressor that are impossible to make completely gas-tight. So it's not unusual to need to add refrigerant occasionally, like over multiple years, but it varies. Although it's probably a little low, I've never HAD to add refrigerant to my 15 yo B5. Back in the 90s I had had a Honda Prelude that needed a top-up nearly every year.

That's why it's generally recommended to use the AC occasionally during extended periods where it would otherwise not operate (winter)... circulating the oil occasionally so the seals don't dry out helps keep a good seal reducing refrigerant seepage.

[jfo]

Automotive AC systems aren't completely closed like a home system is... there are seals such as at the shaft of the compressor that are impossible to make completely gas-tight. So it's not unusual to need to add refrigerant occasionally, like over multiple years, but it varies. Although it's probably a little low, I've never HAD to add refrigerant to my 15 yo B5. Back in the 90s I had had a Honda Prelude that needed a top-up nearly every year.

That's why it's generally recommended to use the AC occasionally during extended periods where it would otherwise not operate (winter)... circulating the oil occasionally so the seals don't dry out helps keep a good seal reducing refrigerant seepage.

I'm not an AC expert but I would suggest that a properly functioning AC system including the compressor, should not leak and is in fact designed to be a closed system. I've only owned one car over about 30 years that actually leaked, and it was a corroded evaporator in a '98 Volvo. If a system has a leak, it is better to locate it and repair, rather than just keep adding refrigerant IMHO.

[dscline]

I'm not an AC expert but I would suggest that a properly functioning AC system including the compressor, should not leak and is in fact designed to be a closed system.

It's simply impossible to maintain a hermetic seal when you have a rotating shaft passing through a seal, particularly when you have a very high pressure on one side, and atmospheric pressure on the other. All things considered, they do pretty well at minimizing refrigerant losses, but it does seep past the seal, even if at an extremely low rate.

Edit: In case you're REALLY interested, here's a whole study on the subject. I haven't read it myself, but it looks like it has some figures for typical loss rates.

[jfo]

It's simply impossible to maintain a hermetic seal when you have a rotating shaft passing through a seal, particularly when you have a very high pressure on one side, and atmospheric pressure on the other. All things considered, they do pretty well at minimizing refrigerant losses, but it does seep past the seal, even if at an extremely low rate.

I do agree with you, just suggesting that it's better to have a trained tech check the system for leaks and repair where necessary rather than assuming it's OK to let it run dry and top up. (not saying you are suggesting this BTW) Allowing the system to run low on refrigerant and the lubricating oil that escapes with it, can possibly lead to expensive compressor problems.

[dscline]

Oh, yes, I definitely agree. You shouldn't let it run dry (though the system shouldn't even allow that, it should stop running once the pressure reaches a low set point). As I promoted in the other AC thread, I would take it to a proper shop even if it was just low on refrigerant. I'm simply saying that it's not completely abnormal to need to add some refrigerant occasionally on an older vehicle. It's just the nature of the beast. Though they can maintain an acceptable charge for a very long time.

[Fburg A4]

You know if t he ac compressor clutch is actually engaging?

[jkownz]

I had this happen to me on my 09 A4 at 30K miles. I brought it to the stealership because it was still under warranty. I had warm air only no matter what setting and how the car was running. It was a sensor that broke underneath the car that controls the AC.

[martian421]

^^

looks like this is the issue that i'm having now. Dealer quoted me $600 to replace and recharge my AC system -

Does anyone know what the going rate is for this type of work? (i posted this on another thread but only got one response there - apologies in advance for the threadcrapping)

[nok]

I'm having the same exact issue in my B8.5 S4 with only 8k miles on it... Went out Sunday night with working AC, returned home without.

Did you find an easy solution or did it require dealer fix? I am still covered by warranty, so at least there's that, but I'm bummed that things are breaking while I've still got new car smell.

[09SLINE]

I had a very similar situation just happen to me and thanks to my VCDS I was able to figure that the G238 sensor had failed and my battery was about to die. These cars are very interesting the deeper you dig. Turns out that when the sensor failed, it told the compressor to shut down. Additionally, with the failing battery the priority of AC was put on the back burner by the computers. The sensor was a quick plug and play and the codes were cleared, AC working good.

[auditd0rk]

Just tossing this out there... I had a similar experience last summer -- a/c appeared to be on, but warm air was blowing out. Scanned for errors and found some a/c compressor open circuit errors. Turned out that a rabbit (or rabbits) had chewed on my wiring harnesses while my car was parked at the airport. I'm not saying it's rabbits, but it could be rabbits :)

[nok]

RESOLUTION UPDATE:

Stopped by Audi service this morning, they had me out the door in about an hour and a half.

Apparently there is a known issue with the A/C Pressure Sensor (TSB# 2020124/11). It was sending incorrect readings and as a result the the AC compressor was shut off. They replaced it under warranty and I was on my way.

The service advisior said that he had seen a few of these cases before, and there are usually two scenarios. If it works out like my case, it's just the sensor and it's a quick replacement job. If they find something more like what autitd0rk described (open circuit error), it takes them a few hours to inspect all of the wiring and possibly more to repair (3+ hours). If you have this issue, definitely hope for scenario #1, lol.

[Highlander1010]

I had this happen to me on my 09 A4 at 30K miles. I brought it to the stealership because it was still under warranty. I had warm air only no matter what setting and how the car was running. It was a sensor that broke underneath the car that controls the AC.

I believe the exact same is going on for my car now. I'm headed in on 9/16. Did you receive a code or see anything in VCDS scans? I have neither, but suspect a sensor failure.

[Highlander1010]

RESOLUTION UPDATE:

Stopped by Audi service this morning, they had me out the door in about an hour and a half.

Apparently there is a known issue with the A/C Pressure Sensor (TSB# 2020124/11). It was sending incorrect readings and as a result the the AC compressor was shut off. They replaced it under warranty and I was on my way.

The service advisior said that he had seen a few of these cases before, and there are usually two scenarios. If it works out like my case, it's just the sensor and it's a quick replacement job. If they find something more like what autitd0rk described (open circuit error), it takes them a few hours to inspect all of the wiring and possibly more to repair (3+ hours). If you have this issue, definitely hope for scenario #1, lol.

NICE! I should have read further first. I'm headed in on 9/16 and think this is exactly what I need fixed.

[Alfrazolam]

This happened to my 2013 A4 at 4K miles.

Mine was caused due to a faulty High Pressure Switch.

Covered under warranty. Took 2 hours to fix.

[JBAeroEngineer]

bumping this due to my entire hvac system not functioning this morning. no fans, heat, a/c, etc. was just working the other morning, no sensor warnings, and i'm sitting at 44k miles

[dscline]

If you have no airflow, my money is on a bad motor / motor controller. These seem to be problematic in these cars. You can find similar psts. It seems that they tend to start getting intermittent... you start your car and nothing, then it magically starts working later like nothing is wrong.

[JBAeroEngineer]

If you have no airflow, my money is on a bad motor / motor controller. These seem to be problematic in these cars. You can find similar psts. It seems that they tend to start getting intermittent... you start your car and nothing, then it magically starts working later like nothing is wrong.

i'm going to check it tonight and take a video just in case it decides to work on Friday when I take it in.

[TimNGobbles]

Does the A4 have a relay that controls the a/c. I had a similar issue on my B5 passat, turned out a relay broke, $70 part and a 2 second repair. I have not gone looking at the internals of the A4 to see if its a similar design..

[piotrowr]

didn't someone on here have the coolant leak out after an HFC install when the new lines were rubbing on the ac coolant lines causing a leak? Check for this visually.

[van462]

bumping this due to my entire hvac system not functioning this morning. no fans, heat, a/c, etc. was just working the other morning, no sensor warnings, and i'm sitting at 44k miles

Also possible your battery may be going out. Energy management may have disabled the HVAC system to conserve power. If you have the coming home and leaving home headlight options enabled see if they are working properly. They are one of the first functions you lose when energy management starts.

[JBAeroEngineer]

Also possible your battery may be going out. Energy management may have disabled the HVAC system to conserve power. If you have the coming home and leaving home headlight options enabled see if they are working properly. They are one of the first functions you lose when energy management starts.

I was just in for 45k service last week, but can double check tonight

[EuropaVin]

Had this problem last week, took it in for service and got the AC pressure sensor replaced under TSB 2020124/12. All good now. A friend of mine had the same problem in the same week as well. Worth noting that I lost my needle sweep on my gauges when I got the car back. Now need to find someone with a Ross tech cable.

[S4_SH1640]

Need help with this issue.

My A/C was working fine and then it slowly got warmer and warmer to eventually i had to blast it at full fan speed (Setting 12) to get the inside temp cool enough.
I Noticed that when i came to a complete stop, the A/C compressor started to make a noise (As if the clutch is having difficulty spinning). But as soon as i would start driving, then it would go back to normal.

Tonight, i made a mistake a recharged it with those advance auto parts bottles (Only because I needed this issue resolved quickly because i am leaving out of the country next week).
As i was charging it, the A/C compressor or something in that area got slightly louder, and then everything shut off, including the engine fan and A/C compressor.

Now it only blows air, not hot, nor cold.

These are the codes/errors i pulled:


Tuesday,26,July,2016,21:23:38:46545
VCDS Version: Release 15.7.4 (x64) Running on Windows 10 x64
www.Ross-Tech.com

Address 5F: Information Electr. Labels: 4E0-035-6xx-5F.clb
Control Module Part Number: 8T1 035 664 C HW: 8T1 035 664 B
Component and/or Version: H-BN-NA H47 0116
Software Coding: 010200000006E1EF01000F0E000000030000
Work Shop Code: WSC 08213 444 50537
VCID: 387F4DCF8BE65AFE86-806C
2 Faults Found:

03276 - Please Check Software Version Management
000 - -
Freeze Frame:
Fault Status: 01100000
Fault Priority: 6
Fault Frequency: 1
Reset counter: 199
Mileage: 233023 km
Time Indication: 0
Date: 2016.07.26
Time: 21:15:01

Freeze Frame:
Voltage: 12.30 V

03157 - Functionality limited due to Communications Disruption
000 - -
Freeze Frame:
Fault Status: 01100000
Fault Priority: 6
Fault Frequency: 1
Reset counter: 199
Mileage: 233023 km
Time Indication: 0
Date: 2016.07.26
Time: 21:15:06

Freeze Frame:
Bin. Bits: 00000001 00000000
Bin. Bits: 00000000 00000000
Bin. Bits: 00000000 00000000
Bin. Bits: 00000000 00000000


Any help is appreciated.

[van462]

Was this after a full scan (auto scan) of modules. Did module 8 (A/C) pass with no errors? When you select the A/C button does the red light come on for a second and then go off, stay on, or not on at all. When the button is selected does the compressor attempt to engage at all? Was the error you have from Module 19 CAN gateway?

[S4_SH1640]

Was this after a full scan (auto scan) of modules. Did module 8 (A/C) pass with no errors? When you select the A/C button does the red light come on for a second and then go off, stay on, or not on at all. When the button is selected does the compressor attempt to engage at all? Was the error you have from Module 19 CAN gateway?

Yes, that was from a full scan. I am not sure about module 8 (A/C) errors. I dont know how to check that.

When i select the A/C button, the red light stays on. When the button is selected (A/C On) the compressor shows no sign of turning on, only did that once or twice, but 9/10 times it wont come on anymore.

And no codes from 19 CAN gateway.

[van462]

Usually if the A/C system cuts off its compressor you will get a red light that shuts off. Then again its not picking up fault codes either. With the A/C set to Lo both electric fans should be turning and the compressor will cycle based off its needs. Did your A/C fill kit have a gauge. Did it indicate the proper PSI for the temperature. You may just need to take it in and have them pull a vacuum on the system and recharge it by refrigerant weight.

[S4_SH1640]

Yea, I pretty much filled it to about where the gauge told me to. I cant remember exact but maybe 50-55 psi. thanks for your help.