AC not working
Thread Starter
AudiWorld Senior Member
Joined: Jan 2010
Posts: 1,668
Likes: 16
From: Brighton, MI
AC not working
1996 B5 A4 2.8 12V AFC quattro auto.
The AC was never working since I got the car.
Not sure if compressor, low pressure, condenser or other leak, module is causing the problem.
Is there a way to narrow it down?
With temps below 50, would the compressor kick in?
Are any of these HVAC codes related to the physical condition of the AC system?
Address 08: Auto HVAC Labels: 8L0-820-043-2D.lbl
Part No: 8L0 820 043 D
Component: A4 KLIMAVOLLAUTOMAT_D75
Coding: 04162
Shop #: WSC 06325
VCID: 29570979F97F
5 Faults Found:
00792 - A/C Pressure Switch (F129)
31-00 - Open or Short to Ground
01297 - Sensor for Vent Temperature; Footwell (G192)
30-00 - Open or Short to Plus
01296 - Sensor for Vent Temperature; Center (G191)
30-00 - Open or Short to Plus
01206 - Signal for Duration of Ignition Off Time
27-10 - Implausible Signal - Intermittent
01582 - Signal for Coolant Temperature
30-00 - Open or Short to Plus
The AC was never working since I got the car.
Not sure if compressor, low pressure, condenser or other leak, module is causing the problem.
Is there a way to narrow it down?
With temps below 50, would the compressor kick in?
Are any of these HVAC codes related to the physical condition of the AC system?
Address 08: Auto HVAC Labels: 8L0-820-043-2D.lbl
Part No: 8L0 820 043 D
Component: A4 KLIMAVOLLAUTOMAT_D75
Coding: 04162
Shop #: WSC 06325
VCID: 29570979F97F
5 Faults Found:
00792 - A/C Pressure Switch (F129)
31-00 - Open or Short to Ground
01297 - Sensor for Vent Temperature; Footwell (G192)
30-00 - Open or Short to Plus
01296 - Sensor for Vent Temperature; Center (G191)
30-00 - Open or Short to Plus
01206 - Signal for Duration of Ignition Off Time
27-10 - Implausible Signal - Intermittent
01582 - Signal for Coolant Temperature
30-00 - Open or Short to Plus
AudiWorld Super User
Joined: May 2002
Posts: 5,138
Likes: 4
From: Redmond WA
1996 B5 A4 2.8 12V AFC quattro auto.
The AC was never working since I got the car.
Not sure if compressor, low pressure, condenser or other leak, module is causing the problem.
Is there a way to narrow it down?
With temps below 50, would the compressor kick in?
Are any of these HVAC codes related to the physical condition of the AC system?
Address 08: Auto HVAC Labels: 8L0-820-043-2D.lbl
Part No: 8L0 820 043 D
Component: A4 KLIMAVOLLAUTOMAT_D75
Coding: 04162
Shop #: WSC 06325
VCID: 29570979F97F
5 Faults Found:
00792 - A/C Pressure Switch (F129)
31-00 - Open or Short to Ground
01297 - Sensor for Vent Temperature; Footwell (G192)
30-00 - Open or Short to Plus
01296 - Sensor for Vent Temperature; Center (G191)
30-00 - Open or Short to Plus
01206 - Signal for Duration of Ignition Off Time
27-10 - Implausible Signal - Intermittent
01582 - Signal for Coolant Temperature
30-00 - Open or Short to Plus
The AC was never working since I got the car.
Not sure if compressor, low pressure, condenser or other leak, module is causing the problem.
Is there a way to narrow it down?
With temps below 50, would the compressor kick in?
Are any of these HVAC codes related to the physical condition of the AC system?
Address 08: Auto HVAC Labels: 8L0-820-043-2D.lbl
Part No: 8L0 820 043 D
Component: A4 KLIMAVOLLAUTOMAT_D75
Coding: 04162
Shop #: WSC 06325
VCID: 29570979F97F
5 Faults Found:
00792 - A/C Pressure Switch (F129)
31-00 - Open or Short to Ground
01297 - Sensor for Vent Temperature; Footwell (G192)
30-00 - Open or Short to Plus
01296 - Sensor for Vent Temperature; Center (G191)
30-00 - Open or Short to Plus
01206 - Signal for Duration of Ignition Off Time
27-10 - Implausible Signal - Intermittent
01582 - Signal for Coolant Temperature
30-00 - Open or Short to Plus
The 96 had a very weak AC core and a lot of them started to leak. I had to replace mine when the car was 7 years old and I wasn't the only one.
They fitted a completely different setup in 97 along with a different climate control box. You can't swap between years either.
Thread Starter
AudiWorld Senior Member
Joined: Jan 2010
Posts: 1,668
Likes: 16
From: Brighton, MI
Those first (3) are AC faults. The AC should run down to about 40F.I would say something in the climate control is un plugged and in addition you have no R134A.
The 96 had a very weak AC core and a lot of them started to leak. I had to replace mine when the car was 7 years old and I wasn't the only one.
They fitted a completely different setup in 97 along with a different climate control box. You can't swap between years either.
The 96 had a very weak AC core and a lot of them started to leak. I had to replace mine when the car was 7 years old and I wasn't the only one.
They fitted a completely different setup in 97 along with a different climate control box. You can't swap between years either.
I plan to pull the HVAC module and check on wires/grounds as well (acting erratically, never blows real hot air).
Will a pressure check tell if R134a is low? If so, is a fill up the next step or can I check for condenser leaks with a simple test (to avoid wasting the fill-up)? On the 98 I tried to fill only to find out that I have a leak, then rigged up a pressure connection to use compressed air to locate the leak (and all the following attempts to plug it failed (brazing with special sticks, 'liquid metal', etc.).
AudiWorld Member
Joined: Aug 2006
Posts: 256
Likes: 0
Since I replace the condenser on my 98 A4 1.8T twice already (stones punches holes in it), the condenser would be my first guess.
I plan to pull the HVAC module and check on wires/grounds as well (acting erratically, never blows real hot air).
Will a pressure check tell if R134a is low? If so, is a fill up the next step or can I check for condenser leaks with a simple test (to avoid wasting the fill-up)? On the 98 I tried to fill only to find out that I have a leak, then rigged up a pressure connection to use compressed air to locate the leak (and all the following attempts to plug it failed (brazing with special sticks, 'liquid metal', etc.).
I plan to pull the HVAC module and check on wires/grounds as well (acting erratically, never blows real hot air).
Will a pressure check tell if R134a is low? If so, is a fill up the next step or can I check for condenser leaks with a simple test (to avoid wasting the fill-up)? On the 98 I tried to fill only to find out that I have a leak, then rigged up a pressure connection to use compressed air to locate the leak (and all the following attempts to plug it failed (brazing with special sticks, 'liquid metal', etc.).
EDIT: the can of R-134a should have a connection on it that only fits on the low side of the compressor. My 2000 has the connection on the passenger's side of the engine bay.
In addition, there should be a schematic sticker that outlines the refrigerant system for reference (ensure your vehicle uses 134a in the first place. i know the newer b5s do but i'm assuming the older ones do also!)
Read the instructions on the can. It say something like perform the charging with the AC running full-blast
Last edited by xsrfsno225x; Mar 16, 2011 at 06:40 AM.
Thread Starter
AudiWorld Senior Member
Joined: Jan 2010
Posts: 1,668
Likes: 16
From: Brighton, MI
On the 98 B5 A5 I did the first replacement, but had a shop do the charging. I did the 2nd replacement and charge on it.
Both times, there was clear evidence of the hole in the condenser from stones. Haven seen a hole in the current issue 96 B5 A4.
Will connect a gauge that I have still around (from the Autozone sets) to see if there is ANY pressure.
If so, on to other potential problem areas.
If no or very low pressure, I will do the 'compressed air' test again (careful, low pressure needed) to see if I can make the leak 'appear' (worked well the last couple of times).
If leak found, get new condenser and prepare for install (with timing belt job maybe) and get another charging kit.
Both times, there was clear evidence of the hole in the condenser from stones. Haven seen a hole in the current issue 96 B5 A4.
Will connect a gauge that I have still around (from the Autozone sets) to see if there is ANY pressure.
If so, on to other potential problem areas.
If no or very low pressure, I will do the 'compressed air' test again (careful, low pressure needed) to see if I can make the leak 'appear' (worked well the last couple of times).
If leak found, get new condenser and prepare for install (with timing belt job maybe) and get another charging kit.
AudiWorld Super User
Joined: Jun 2008
Posts: 2,284
Likes: 100
From: Fallbrook, CA
After you do your compressed air test, you are evacuating with a vacuum pump? If you have leftover air in the system, refrigerant won't liquefy, which how an AC system has to work. Air in the system also introduces water, which will cause the expansion orifice to clog with ice, if the receiver/dryer doesn't catch all of it. Regarding how to know if there is still pressure, you can always check for pressure in a very crude way by pushing on the test port's Schrader valve.
Recharging the '96 is easy with the MasterCool adapter available from NAPA stores.
Recharging the '96 is easy with the MasterCool adapter available from NAPA stores.
Thread Starter
AudiWorld Senior Member
Joined: Jan 2010
Posts: 1,668
Likes: 16
From: Brighton, MI
After you do your compressed air test, you are evacuating with a vacuum pump? If you have leftover air in the system, refrigerant won't liquefy, which how an AC system has to work. Air in the system also introduces water, which will cause the expansion orifice to clog with ice, if the receiver/dryer doesn't catch all of it. Regarding how to know if there is still pressure, you can always check for pressure in a very crude way by pushing on the test port's Schrader valve.
Recharging the '96 is easy with the MasterCool adapter available from NAPA stores.
Recharging the '96 is easy with the MasterCool adapter available from NAPA stores.
Does this mean that a system that HAD a leak cannot be charged with the DIY charging kits and has to be done by a shop with 'evacuator'?
Important to know. So far I thought I
- check pressure
- no pressure ==> potential leak ==> pressurize with air ==> find and confirm leak
- fix leak or install new condensor
- buy DIY charing kit
- fill up
- enjoy cold air
Not so?
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AudiWorld Super User
Joined: Jun 2008
Posts: 2,284
Likes: 100
From: Fallbrook, CA
To the best of my knowledge, you have to pull a vacuum for a period of time, which also tends to dry the desiccant in the receiver/dryer. I used to work for Mazda's R&D center here in CA, on A/C systems, and did lots of installations. That was R12 refrigerant at the time, but same principle.
You might be advised to go to an A/C specialist anyway, if you suspect a leak. They can find leaks with UV light and by using dyes in the system.
You might be advised to go to an A/C specialist anyway, if you suspect a leak. They can find leaks with UV light and by using dyes in the system.
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Joined: May 2002
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From: Redmond WA
Nope, did not evacuate with vacuum, wouldn't know how to. I only pressurized the system when there was no pressure (and therefore no refrigerant in there, hence the need to pressurized to find a leak; if system has pressure, I would assume there is no leak).
Does this mean that a system that HAD a leak cannot be charged with the DIY charging kits and has to be done by a shop with 'evacuator'?
Important to know. So far I thought I
- check pressure
- no pressure ==> potential leak ==> pressurize with air ==> find and confirm leak
- fix leak or install new condensor
- buy DIY charing kit
- fill up
- enjoy cold air
Not so?
Does this mean that a system that HAD a leak cannot be charged with the DIY charging kits and has to be done by a shop with 'evacuator'?
Important to know. So far I thought I
- check pressure
- no pressure ==> potential leak ==> pressurize with air ==> find and confirm leak
- fix leak or install new condensor
- buy DIY charing kit
- fill up
- enjoy cold air
Not so?
Last edited by AudiMick; Mar 16, 2011 at 12:22 PM.
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