K9COP

Hi guys, my GF's 2.7TT A6 (C5) has no cold A/C. I think I have two problems with it.
1) the 'ECON' switch stays illuminated (saw on a searched thread that may be a problem), and

2) the VCDS show a trouble code with the HVAC (full scan below). The code is:

"1 Fault Found:
01592 - Air Quality Sensor (G238)
57-00 - Electric Circuit Failure"

Would this be able to 'disable' the A/C please?

Not familiar with her car (I have a D3) so any help very gratefully received...

Thanks guys,

K9

Full Scan:

Tuesday,15,May,2012,21:18:05:40451
VCDS Version: Release 11.11.3 (x64)
Data version: 20120401



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: 4B - Audi A6 C5
Scan: 01 02 03 06 08 15 16 17 18 22 34 35 36 37 45 55 56 57 65 67
75 76 77

VIN: WAULD64B82N015963
-------------------------------------------------------------------------------
Address 01: Engine Labels: 078-907-551-AZA.lbl
Part No: 4B0 907 551 AK
Component: 2.7l V6/5VT G 0001
Coding: 06712
Shop #: WSC 02325
VCID: 6DDBF8D7278ADF1
WAULD64B82N015963 AUZ7Z0A1881780

2 Faults Found:
16815 - Warm Up Catalyst; Bank 2
P0431 - 35-00 - Efficiency Below Threshold
16805 - Warm Up Catalyst; Bank 1
P0421 - 35-00 - Efficiency Below Threshold
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 4B0-614-517.lbl
Part No: 4B0 614 517 H
Component: ABS/ESP allrad 1328
Coding: 06395
Shop #: WSC 02325
VCID: 2649C7FBC2FC2C9

No fault code found.

-------------------------------------------------------------------------------
Address 06: Seat Mem. Pass Labels: None
Part No: 4B0 959 760 C
Component: Sitzmemory R1 BF 0102
Coding: 00003
Shop #: WSC 00000
VCID: 2D5B38D7E70A1F1

No fault code found.

-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: 4B0-820-043-MY2.lbl
Part No: 4B0 820 043 AD
Component: A6-Klimavollautomat 0104
Coding: 00010
Shop #: WSC 02325
VCID: 5CBDA513CC30A69

1 Fault Found:
01592 - Air Quality Sensor (G238)
57-00 - Electric Circuit Failure

-------------------------------------------------------------------------------
Address 15: Airbags Labels: 4B0-959-655-AI84.lbl
Part No: 4B0 959 655 N
Component: Airbag 8.4E 3000
Coding: 0000307
Shop #: WSC 02325 785 00200
VCID: 3B7F068F797E811

No fault code found.

-------------------------------------------------------------------------------
Address 16: Steering wheel Labels: 4B0-907-487.lbl
Part No: 4B0 907 487 C
Component: Lenkradelektronik D01
Coding: 00002
Shop #: WSC 02325
VCID: 2C5D35D3DC10169

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments Labels: 4B0-920-xxx-17.lbl
Part No: 4B0 920 983 FX
Component: KOMBI+WEGFAHRS. VDO D17
Coding: 02264
Shop #: WSC 08213
VCID: 830F3E6F910EB91
WAULD64B82N015963 AUZ7Z0A1881780

No fault code found.

-------------------------------------------------------------------------------
Address 35: Centr. Locks Labels: 4B0-962-258.lbl
Part No: 4B0 962 258 J
Component: Central Lock/Alarm D34
Coding: 15885
Shop #: WSC 08213
VCID: 306521A3F038729

2 Faults Found:
01560 - Passenger Door
59-10 - Can't Unlock - Intermittent
01562 - Right Rear Door
59-10 - Can't Unlock - Intermittent

-------------------------------------------------------------------------------
Address 36: Seat Mem. Drvr Labels: None
Part No: 4B0 959 760 B
Component: Sitzmemory R1 F 0101
Coding: 00001
Shop #: WSC 00000
VCID: 2C5D35D3DC10169

No fault code found.

-------------------------------------------------------------------------------
Address 45: Inter. Monitor Labels: None
Part No: 4B0 951 178 A
Component: Innenraumueberw. D04
Coding: 00101
Shop #: WSC 02325
VCID: 2649C7FBC2FC2C9

No fault code found.

-------------------------------------------------------------------------------
Address 55: Xenon Range Labels: 4Z7-907-357.lbl
Part No: 4Z7 907 357
Component: dynamische LWR D06
Coding: 00050
Shop #: WSC 02325
VCID: 040DBD7314003E9

1 Fault Found:
00776 - Level Control System Sensor; Left Front (G78)
31-00 - Open or Short to Ground

-------------------------------------------------------------------------------
Address 56: Radio Labels: 8E0-035-1xx-56.lbl
Part No: 4B0 035 195 J
Component: symphony II NP2 0008
Coding: 00201
Shop #: WSC 00000
VCID: 2757CAFFC5F6351

No fault code found.

-------------------------------------------------------------------------------
Address 76: Park Assist Labels: 8Z0-919-283.lbl
Part No: 8Z0 919 283
Component: Parkingsyst. A6 USA D08
Coding: 00126
Shop #: WSC 02325
VCID: 0201BB6B0E14309

1 Fault Found:
01550 - Signal for Reverse Gear
27-10 - Implausible Signal - Intermittent

End ---------------------------------------------------------------------

4Driver4

My guess is low freon due to a leak.

Is there any cool air at all from the passenger side?

Prospeeder

It doesnt look like it can. heres the description and operation. What you need to do is look at the Measure blocks and find compressor cut off and see what number is in the field. 0-22 are the codes. If it was low on refrigerant, they throw a actual code and econ light stays on. Code usually is Refrigerant pressure sensor low signal.




A/C cut-off Codes

0 = Compressor on (no shut-off requirement of the A/C compressor detected)

1 = Compressor off (refrigerant pressure was or is too high)

2 = Compressor off (blower motor circuit)

3 = Compressor off (refrigerant pressure was or is too low)

4 = Compressor off (display not currently intended)

5 = Compressor off (no engine start or no engine speed detected)

6 = Compressor off (A/C system switched off, ECON-mode activated)

7 = Compressor off (A/C system switched off, blower switch in position 0)

8 = Compressor off (outside temperature was less than 1.5°C and is still less than 2.5 °C)

9 = Compressor off (display not currently intended)

10 = Compressor off (Low voltage)

11 = Compressor off (display not currently intended)

12 = Compressor off (shut-off request from Engine Control Module (ECM) via CAN)

13 = Compressor off (voltage supply terminal 30 too high)

14 = Compressor off (Evaporator Temperature)

15 = Compressor off (display not currently intended)

16 = Compressor off (activation A/C Compressor Regulator Valve -N280- implausible)

17 = Compressor off (no signal or implausible signal from High Pressure Sensor -G65-)

18 = Compressor off (engine speed too high at standstill)

19 = Compressor off (shutoff request from Vehicle Electrical System Control Module via CAN)

20 = Compressor off (refrigerant loss-currently V8 Touareg only)

21 = Compressor off (Outside Temp < 2 degrees C, without recirc mode on)

22 = Compressor off (Outside Temp < 2 degrees C, Inside Temp. < 10 degrees C)







The sensor for air quality recognizes pollutants in the recirculating air (mostly gasoline and or diesel exhaust) and relies on the A/C Control Head -E87- to switch to the recirculating mode.
The A/C Control Head -E87- receives a signal from the Sensor for air quality -G238- from which the type and amount of air pollution is determined. Depending on the outside temperature and the amount of air pollution, the A/C control head then decides:
At an outside temperature greater than approx.: +2 °C (36 °F) the recirculating air mode is switched on when there is only a slight increase in pollutants. switched in air recirculation mode
At outside temperature between approx. +2 °C and approx. -8 °C the change-over to the recirculating air mode is only performed when the pollutant concentration strongly increases (compressor simultaneously switched on).
At an outside temperature of -8 °C (-18 °F) a change over occurs after a severe increase of pollutants concentration, and only for 15 seconds (the compressor is not shut off).
If the concentration drops, the climate control system switches over to the fresh air mode.
The function "Automatic air recirculation" can be switched off at any time. If the function is active and a request for "Automatic air recirculation" is present the compressor is also switched on when outside temperatures are lower than + 2 °C. Compressor operation is not possible with temperatures lower than approx.-8 °C .
On vehicles with "Automatic air recirculation", up to a temperature of approx. - 8 °C the compressor can be switched on when recirculated air was manually switched on (via recirculation button).
To ensure that the A/C does not operate constantly in the recirculating air mode in areas with a consistently higher pollution, the sensor is self learning (it adjusts its sensitivity to the environmental conditions).
If outside air pollution load remains high for longer period of time, the sensor starts to adapt itself to the changing environmental condition through an adaptation program (learning program), the air recirculation request in evenly polluted ambient air is therefore generally shorter than 12 minutes . The climate control system may also operate a longer period of time in air recirculation mode, if more load peaks occur after another.
A specific amount of time is needed for the A/C flaps to change over. In the event that a sudden increase in pollutants is encountered (e.g. when driving through a diesel exhaust cloud) gas-forming pollutants can be taken in with the fresh air into the passenger compartment until the flaps can be closed. For this reason, a dust- and pollen filter is installed with a charcoal layer A filter that has become saturated with pollutants is no longer effective and needs to be replaced.
In order to avoid a quick shifting from the recirculating-/fresh air flap, a slight increase in pollutants entering with recirculating air will not allow for immediate shifting (the sensor does not send a request to A/C Control Head --E87-). The filtering of the charcoal insert in the dust- and pollen filter will be sufficient.
In order to avoid quick shifting from the recirculating air/fresh air flap, the requirement from the sensor for "Automatic air recirculation" mode is at least 25 seconds (minimum duration period), especially if the pollutant concentration has been reduced considerably so that recirculating air mode is no longer necessary.
If the compressor is shut-off (e.g. in "Econ" mode" so that the windows do fog up, the maximum duration of the "Automatic air recirculation" mode from A/C control head -E87- is limited to approx. 15 seconds .
In order to defrost windows as quick as possible, recirculating air mode is not possible with A/C Control Head -E87- in the defrost operating mode.
The Sensor for air quality -G238- requires approx. 30 seconds to become operational after switching the ignition on (warm-up time). During this time there is no requirement from the sensor to A/C Control Head -E87- for "Automatic air recirculation" mode.
The Sensor for air quality -G238- contains a highly sensitive electronic component, which can be damaged if it comes in direct contact with solvents, fuels or chemicals. Therefore, do not install sensors which have come in contact with such substances.

SloopJohnB@mac.com

Maybe, maybe not. My 2K4.2A6 runs low on R134A and it just blows warm air. The econ light doesn't stay on; it will if I push the button, then the compressor doesn't run. But pushing the button again turns off the econ light and the compressor runs.

Thing is, compressor can run without being low enough to trigger the low pressure cutoff yet still blow warm air. So first thing is to put enough R134A+ in to get the compressor going (the cheap 16oz can is probably enough and it has foolproof connectors...you can't hook it up to the high side) and then put the rest of the can in there. I've even been know to turn the can upsides down for a few seconds, then turn it right side up, repeat until can is empty. Get the refill can with lubricant already in it. You have to get about 40 psi on the low side with the compressor running to get cold air (around 80F outside temp).

K9COP

The guage on the can held steady at 55psi (ambient temp 85 degrees) and still no cold air. Am I even looking at the compressor correctly? I'm assuming it's the cylindrical thing at the top of the engine, under the removable 'V6 BiTurbo' shield. If so, the centre of the uppermost pulley is rotating no matter what. Air on, air off, fan on, fan off, no matter what temp is selected....surely that means the compressor is rotating?

what do I do next?

K9

4Driver4

Stop guessing and take it to a shop.

It really should be evacuated and filled with a measured charge. At this point it is either overcharged or undercharged.

SloopJohnB@mac.com

At this point I have to agree w/4D4....if you have to guess whether you're looking at the compressor correctly, or even if you don't know or cannot comprehend what a compressor is, you're out of your mechanical depth and need to to a shop.

K9COP

I really should take the 'cop' part out of my user name.

A simple 'yes the middle of the pulley should be stationary when the compressor is off' would have sufficed. I'm trying to eliminate if I have an a/c compressor clutch fault, or if the default behaviour of the pulley/clutch assembly is that it rotates all the time.

55psi @85 degrees is within tolerances for the R134-A as supplied on the guage that came with the can. I've read elsewhere on here that a charge of at least 40psi is required to cause the a/c compressor to work, and I have that, according to the guage that came with the refill (with lubricant) can. I'm not sure I'm out of my depth particularly, just asking for some more specific info.

Thanks,

K9

SloopJohnB@mac.com

LOL on the cop issue. Just because you're paranoid doesn't mean they're not out to get you. Paranoia is a survivor trait. Keep your eyeballs on. I didn't even twig to the K9COP sig.

The low pressure switch is a lot lower than 40psig...it works at 15psig I know for sure on my cars.

As a general rule, the center of the pulley rotates with the clutch on...so yes, the compressor is doing its thing and electrically it sounds like your compressor is being turned. However, if you're not getting cold air there are many possibilities ranging from a clogged expansion valve/orifice to a failed compressor/seals to heat from the engine/heater core overriding the evaporator output. One check is to put your hand on the low pressure line and if it's cold, something else is stopping cold air from coming out your vents, like a failed flap motor somewhere in the AC/heating system or a coolant shut-off valve (IIRC the coolant to the heater core is supposed to be shut off when AC is on and temperature is above the set temperature), isn't and the heater is reheating the cold air. If you don't have a cold low pressure side refrigerant isn't circulating and that's most likely a clogged expansion valve/orifice.

At that point it's a technicians job to replace the orifice/filter as well as the receiver/dryer, suck and recharge the system. If the orifice is clogged with metal shavings it's likely a compressor replacement as well with a complete system flush and hopefully not an evaporator and condenser replacement as well (if they get clogged with shavings from an internally failed compressor it's almost impossible to clean them out).

So it sounds like you've got more than a compressor clutch issue.

Prospeeder

dont forget alot of these cars use a clutchless compressor, so they run all the time. Theres a variable displacment block inside that meters a/c output when voltage is supplied. If the compressor is getting voltage, but pressures stay static, the compressor is junk or the expansion valve is stuck open.