If you where to hook up a set of AC guages to the Hi/Lo pipes, are their any typical static / dynamic pressure range readings on the Hi/Lo sides for VW cars? The typically scenario I'm thinking of is testing the pressures to see if topping up is reqd
Tis’ the HVAC Season
- Thread starter DrPeter
- Start date
- Status
- Hi...
Take a look at the 1st post, I had recently added the 'G65 Pressure vs. Temperature chart'
So these are the typical pressures you would see when key is on, engine is off, these are the static system pressures.
With a quality A/C Manifold Gauge Set you should see the same pressures readings, less 1 bar(14.7psi) and the reason that there is less 1 bar of pressure is that the chart reflects the G65 readings in the MVBs and the G65 will read 1 bar (14.7psi) when NOT under pressure, at sea level. So always take away '1 bar' from the MVB reading to get a 'gauge' reading equivalent.
For example:
Outside temperature = 30C (86F)
MVB for G65 reads = 7.0 bar (103 psi)
A/C Gauges read = 6.0 bar (88 psi)
- Typical 'dynamic' pressures differ because there are a lot of different factors that can influence the gauge readings. There are some excellent books written on the subject.
My favorite book is titled 'Modern Refrigeration and Air Conditioning'
You should NOT "top off" any AC system with first knowing how much refrigerant is the system, doing so can easily over charge the A/C system and cause compressor damage!
You can not compress liquid refrigerant with an automotive compressor and an overcharged A/C system may send liquid refrigerant back to the compressor causing stress, cracking of the internal components which maybe difficult to see or detect.
If you do not have a recovery/charging system.....
- You can start with an empty system, it is recommended to pull a vacuum on the system to remove(boil) moisture and assist in charging.
- Using a scale record the gross weight of the container of refrigerant.
- Then slowly charge the system while periodically checking the weight of the container until the desired weight has been transferred.
See the under hood A/C sicker
Be safe, stay cool.....
drpeter
MK4 A/C quick and dirty checking:
| A/C compressor clutch? | Radiator Fans? | Sensor |
| Nope | Nope | Ambient Temp Sensor (F38) @ T14/5 and T14/14 |
| Nope | Nope | Signal from the Instrument Cluster @ T14/13 |
| Nope | Nope | High Side Pressure Sensor (G65) @ T14/2 |
| Nope | Yes | Issue with A/C clutch circuit (N25) |
| Nope | Yes | ECM/TCM signal @ T14/3 |
- If the Ambient Temp Sensor (F38) is bad, unplugging it and shorting the terminals together will fix the A/C system after 2 minutes @ idle.
- While the Fan Control Module (J293) is dumb as dirt, it does monitor amp draw of the A/C Clutch (N25). If the draw is out of factory design (open or short circuit), the Fan Control Module (J293) can cut power to the A/C Clutch (N25).
- A/C Clutch (N25) should be about 4.5 ohms.
- Terminals can rot inside the terminal housing. Using a hook tool, gently tug on each of the wires to verify they have not come apart.
Greetings all,
Found this thread while googling, figured I'd post here rather than start a new thread. I am having problems with the AC on my 2004 Audi Allroad (4.2L) I just finished an engine swap in it, it was a 2.7T and I put a 4.2L in it. With respect to the AC, I've done the following:
1.) replaced condenser and high pressure switch
2.) put entire system in vacuum, vacuum held for 1 hour
3.) Charged system with 19OZ of Freon. (filled compressor with 8oz of oil before assembly)
I recoded the HVAC head for the N280 regulator valve instead of the clutch setup of the 2.7T compressor. Swapped over the evaporator outlet sensor. As you can see from the screen shots below, I'm getting an ambient air temp reading, a high pressure sensor reading, a evap outlet temp reading and a intake air temp reading. I have no fault codes stored in the HVAC head. I have rang out the N280 regulator valve on the compressor and it was 10 ohms. I have grounded Connector D PIN 8 at the HVAC head and I can hear N280 regulator valve clicking on and off. I have 14.35VDC at the compressor electrical connector when the vehicle is running. If I jump N280 to power when the vehicle is running I can get cold air to start coming out the vents. For some reason the HVAC head is just not requesting the compressor to turn on. I have two different HVAC heads, same issue with both.
I did find one thing, there is a compressor shutdown code of "10" (low voltage) but as I mentioned above, I've checked voltage at the compressor, so I'm not sure what else this error could mean. I don't know if there's some adaption I have to go through or some procedure for clearing out the shutdown codes. Any help would be appreciated!!
Found this thread while googling, figured I'd post here rather than start a new thread. I am having problems with the AC on my 2004 Audi Allroad (4.2L) I just finished an engine swap in it, it was a 2.7T and I put a 4.2L in it. With respect to the AC, I've done the following:
1.) replaced condenser and high pressure switch
2.) put entire system in vacuum, vacuum held for 1 hour
3.) Charged system with 19OZ of Freon. (filled compressor with 8oz of oil before assembly)
I recoded the HVAC head for the N280 regulator valve instead of the clutch setup of the 2.7T compressor. Swapped over the evaporator outlet sensor. As you can see from the screen shots below, I'm getting an ambient air temp reading, a high pressure sensor reading, a evap outlet temp reading and a intake air temp reading. I have no fault codes stored in the HVAC head. I have rang out the N280 regulator valve on the compressor and it was 10 ohms. I have grounded Connector D PIN 8 at the HVAC head and I can hear N280 regulator valve clicking on and off. I have 14.35VDC at the compressor electrical connector when the vehicle is running. If I jump N280 to power when the vehicle is running I can get cold air to start coming out the vents. For some reason the HVAC head is just not requesting the compressor to turn on. I have two different HVAC heads, same issue with both.
I did find one thing, there is a compressor shutdown code of "10" (low voltage) but as I mentioned above, I've checked voltage at the compressor, so I'm not sure what else this error could mean. I don't know if there's some adaption I have to go through or some procedure for clearing out the shutdown codes. Any help would be appreciated!!
- Joined
- Jun 26, 2014
- Messages
- 1,436
- Reaction score
- 2,156
- Location
- Newcastle, England
- VCDS Serial number
- C?ID=24330
There'll be a MVB that gives what the 08-HVAC head thinks the vehicle voltage is. Would you check that and report back please?
Here's a few more images. I went through the first 20 groups in the measurement blocks of my HVAC head. After around 20 they all just came up as errors. I only found one pertaining to voltage. I see one is reading 0V but is noted as pin 75. Is this pin 75 of the main ECU? I don't think my HVAC head has a pin 75, just four connectors (A/B/C/D) with not more than probably 20 positions on the largest connector. (approx)
[/URL][/IMG]
[/URL][/IMG]
I'll put my AC manifold gauges back on it tonight, but I believe the low side was reading around 60-70PSI and the high side was about 100PSI. If I externally powered the compressor regulator valve the high side pressure would start to climb and the low side would start to fall. As soon as I removed power though it would go right back to the original readings.
- Joined
- Jun 26, 2014
- Messages
- 1,436
- Reaction score
- 2,156
- Location
- Newcastle, England
- VCDS Serial number
- C?ID=24330
Your refrigerant gas pressures look fine; so I'd leave them alone for now. The Compressor Shut-Off criteria is exactly why the N280 is not engaging. If it was due to gas pressure; you'd get a Shut-Off code of 3. The control head definitely thinks it's voltage is too low. Have you potentially disturbed a wire in changing the head? All plug-couplers pushed fully home? All supply fuses to the HVAC intact?
Terminal 75 is not a pin or chamber number, it's the DIN vehicle terminal number, like 30 is battery positive, 15 ignition live, 31 ground etc. T75 actually refers to the radio.
What I'd suggest:
Start a new thread in 'Car Repair Support' or 'General VW/Audi Repair' (or Uwe could split and move your posts here)
Post a full Auto-Scan
Verify that even though your control head accepted the coding, that the hardware version is compatible with an N280 compressor.
If so, get the Wiring Diagram for your model and start tracing wires.
Terminal 75 is not a pin or chamber number, it's the DIN vehicle terminal number, like 30 is battery positive, 15 ignition live, 31 ground etc. T75 actually refers to the radio.
What I'd suggest:
Start a new thread in 'Car Repair Support' or 'General VW/Audi Repair' (or Uwe could split and move your posts here)
Post a full Auto-Scan
Verify that even though your control head accepted the coding, that the hardware version is compatible with an N280 compressor.
If so, get the Wiring Diagram for your model and start tracing wires.
Thanks for this information. I will look into everything you've noted and if I can't get anywhere I will post as a new question in one of the forums you suggested. With respect to what you said, I can say that it's probably not a hardware version compatibility issue; reason being is one of my HVAC heads is the one which was used when the car was a 2.7T (worked fine for 6 years and the one I attempted to recode) and the second HVAC head I have is the one that actually came out of the donor car which had the 4.2L & compressor w/regulator. So that should have been a perfect hardware/software match for the 4.2L engine/compressor.
There's a very good chance I am missing a wire or I need to move wires(s) around going to my HVAC head. Because I swapped from the 2.7T to the 4.2L, I basically am running a 4.2L engine off the chassis harness of a 2.7T car. I did have to add in wires for the evaporator outlet sensor and many for the cooling fan circuits. I think I'm really close but I may be missing something. I can look at three of the four HVAC connectors in my part out car and do a comparison of what pins are populated and which ones aren't. But one connector is gone. I may also have to try and find a complete wiring diagram/pinout for the HVAC head.
The AC does work momentarily when I recode the HVAC head as a compressor clutch but ultimately I get a code thrown in the HVAC head for a short on the clutch. I'm guessing this is because with the clutch, the HVAC head is just driving a relay (30mA?) and when it attempts to drive the regulator valve the current is probably spiking. (14V/10ohm=1.4A) I think my work around could be to code the HVAC head as a clutch compressor and let the original compressor clutch relay operate the N280 regulator valve. It'd be great if that worked but probably wouldn't.
A/C is working!!!!! 
I've been picking away at this problem for two weeks......
Thanks very much for your comments; you were right, I was missing a voltage at the HVAC head. I found it in the schematics at work today and tested the theory out when I got home. Turns out on a 2.7T car with a clutch compressor and clutch relay, the relay not only picks the clutch but it also provides a feedback signal to the HVAC head. On the 4.2L with the N260 regulator valve, that feedback signal at the HVAC head is just tied to a constant voltage supply. As soon as I tied it high, the "10" shut off criteria (low voltage) error disappeared and that missing voltage (pictured above) showed up at 14.4V. (terminal 75)
So F'ing happy.
Thanks!!
I've been picking away at this problem for two weeks......
Thanks very much for your comments; you were right, I was missing a voltage at the HVAC head. I found it in the schematics at work today and tested the theory out when I got home. Turns out on a 2.7T car with a clutch compressor and clutch relay, the relay not only picks the clutch but it also provides a feedback signal to the HVAC head. On the 4.2L with the N260 regulator valve, that feedback signal at the HVAC head is just tied to a constant voltage supply. As soon as I tied it high, the "10" shut off criteria (low voltage) error disappeared and that missing voltage (pictured above) showed up at 14.4V. (terminal 75)
So F'ing happy.
Thanks!!
Anyone have more information on Compressor code 12?
Backstory:
Started having AC issues last Fall (code 00819).. replaced the High Pressure sensor (What the original VCDS code said), no dice. Chased the issue.. replaced the RCV on the compressor, and the AC control unit in the dash.. never fixed the issue.
Fast forward to now and I'm revisiting this issue.. found a crashed 2006 Jetta TDI and bought the compressor off it.. replaced the compressor, Same high pressure code, so I replaced the sensor again (replacing the new one I bought last year). This fixed the 00819 High Pressure sensor code!
AC shop filled the Freon and everything.. now I'm getting a code 12 = Compressor OFF: Shut-Off requested by Engine Control. No fault codes...
The compressor I replaced mine with was not an identical part. Even though it was off the same year/make/model jetta. Both compressors are Sanden. The original had a C-clip to remove the RSV valve, this one does not.
Does the compressor version make a difference?
Called O'rileys auto parts and they only have one version, so I'm leaning towards no..
I do not know the source of my AC control unit - bought off ebay. It has the exact same buttons though, Climatic with heated seats.
Sometimes I will see a code saying Refrigerant pressure too low, however the shop said they filled it to spec..
AC Clutch Relay Control Circuit Output test: 3.91-4.23 BAR, no change with it On/Off
Pictures of VCDS Output Screens:
https://www.dropbox.com/s/wh3k9xrdo3p2bqs/1.png?dl=0
https://www.dropbox.com/s/s1ghdy03kjzja91/2.png?dl=0
https://www.dropbox.com/s/fumfxdzhwmudaws/3.png?dl=0
Full VCDS Scan:
Thoughts? What can cause a code 12?
Backstory:
Started having AC issues last Fall (code 00819).. replaced the High Pressure sensor (What the original VCDS code said), no dice. Chased the issue.. replaced the RCV on the compressor, and the AC control unit in the dash.. never fixed the issue.
Fast forward to now and I'm revisiting this issue.. found a crashed 2006 Jetta TDI and bought the compressor off it.. replaced the compressor, Same high pressure code, so I replaced the sensor again (replacing the new one I bought last year). This fixed the 00819 High Pressure sensor code!
AC shop filled the Freon and everything.. now I'm getting a code 12 = Compressor OFF: Shut-Off requested by Engine Control. No fault codes...
The compressor I replaced mine with was not an identical part. Even though it was off the same year/make/model jetta. Both compressors are Sanden. The original had a C-clip to remove the RSV valve, this one does not.
Does the compressor version make a difference?
Called O'rileys auto parts and they only have one version, so I'm leaning towards no..
I do not know the source of my AC control unit - bought off ebay. It has the exact same buttons though, Climatic with heated seats.
Sometimes I will see a code saying Refrigerant pressure too low, however the shop said they filled it to spec..
AC Clutch Relay Control Circuit Output test: 3.91-4.23 BAR, no change with it On/Off
Pictures of VCDS Output Screens:
https://www.dropbox.com/s/wh3k9xrdo3p2bqs/1.png?dl=0
https://www.dropbox.com/s/s1ghdy03kjzja91/2.png?dl=0
https://www.dropbox.com/s/fumfxdzhwmudaws/3.png?dl=0
Full VCDS Scan:
Code:
Tuesday,25,April,2017,17:10:35:16619
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 17.1.3.0 (x64)
Data version: 20170320 DS267.7
www.Ross-Tech.com
VIN: 3VWST71K06M800471 License Plate:
Chassis Type: 1K (1K0)
Scan: 01 03 08 09 0F 15 16 17 19 25 42 44 46 52 56 62 72 7D
VIN: 3VWST71K06M800471 Mileage: 333110km-206984miles
00-Steering Angle Sensor -- Status: OK 0000
01-Engine -- Status: OK 0000
03-ABS Brakes -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: OK 0000
0F-Digital Radio -- Status: Malfunction 0010
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: Malfunction 0010
25-Immobilizer -- Status: OK 0000
42-Door Elect, Driver -- Status: OK 0000
44-Steering Assist -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
56-Radio -- Status: Cannot be reached 1100
62-Door, Rear Left -- Status: OK 0000
72-Door, Rear Right -- Status: OK 0000
7D-Aux. Heat -- Status: OK 0000
-------------------------------------------------------------------------------
Address 01: Engine Labels: 038-906-016-BEW.lbl
Part No SW: 03G 906 016 AB HW: 028 101 223 8
Component: R4 1,9L EDC G000SG 7550
Revision: --H02--- Serial number: VWZ7Z0F3630183
Coding: 0050071
Shop #: WSC 66565 257 00032
VCID: 63C5F2D3A215535994-8036
No fault code found.
Readiness: 0 0 0 0 X
-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 1K0-907-379-MK60-F.lbl
Part No SW: 1K0 907 379 AA HW: 1K0 907 379 AA
Component: ESP FRONT MK60 0102
Revision: 00H13001
Coding: 0021122
Shop #: WSC 00066 000 00000
VCID: 71E9889B68E9F1C916-8024
No fault code found.
-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: 1K0-820-047.lbl
Part No SW: 1K0 820 047 JM HW: 1K0 820 047 JM
Component: Climatic PQ35 142 1212
Revision: 00142032 Serial number: 00000000000000
Shop #: WSC 00000 000 00000
VCID: 78FFB5BF0B93A081D1-802C
No fault code found.
-------------------------------------------------------------------------------
Address 09: Cent. Elect. Labels: 3C0-937-049-23-M.lbl
Part No SW: 3C0 937 049 D HW: 3C0 937 049 D
Component: Bordnetz-SG H37 1002
Revision: 00H37000 Serial number: 00000000297865
Coding: 14018E234004100000140000001400000008730B5C
Shop #: WSC 08701 444 58591
VCID: 2A5B5FF785BFC21197-807E
Subsystem 1 - Part No: 1K1 955 119 C Labels: 1KX-955-119.CLB
Component: Wischer VW350 013 0402
Coding: 00063445
Shop #: WSC 08701
No fault code found.
-------------------------------------------------------------------------------
Address 0F: Digital Radio Labels: 8E0-035-593-SIR.lbl
Part No SW: 8E0 035 593 D HW: 8E0 035 593 D
Component: SDAR SIRIUS H03 0060
Revision: 00000000 Serial number: AUZ4Z7F1025245
Shop #: WSC 00000 000 00000
VCID: 2A5B5FF785BFC21197-807E
1 Fault Found:
01304 - Radio
008 - Implausible Signal
Freeze Frame:
Fault Status: 01101000
Fault Priority: 5
Fault Frequency: 1
Reset counter: 27
Mileage: 333098 km
Time Indication: 0
Date: 2000.00.00
Time: 10:46:52
-------------------------------------------------------------------------------
Address 15: Airbags Labels: 1K0-909-605.lbl
Part No SW: 1K0 909 605 P HW: 1K0 909 605 P
Component: 39 AIRBAG VW8R 032 7900
Revision: 03032000 Serial number: 0038FD04J0W8
Coding: 0013113
Shop #: WSC 00066 000 00000
VCID: 397970BB70197989EE-806C
Subsystem 1 - Part No: 1K0 959 339 E
Component: BF-Gewichtsens. 006 0005
Subsystem 2 - Serial number: 6332MSME0D5E626CT
Subsystem 3 - Serial number: 6342MSME0D1E757CV
Subsystem 4 - Serial number: 6351HSME09376421%
Subsystem 5 - Serial number: 6361HSME09374C72C
Subsystem 6 - Serial number: 63727SME09264039-
Subsystem 7 - Serial number: 63827SME0926610C/
No fault code found.
-------------------------------------------------------------------------------
Address 16: Steering wheel Labels: 1K0-953-549-MY8.lbl
Part No SW: 1K0 953 549 AH HW: 1K0 953 549 AH
Component: J0527 034 0070
Coding: 0000021
Shop #: WSC 00066 000 00000
VCID: 78FFB5BF0B93A081D1-802C
No fault code found.
-------------------------------------------------------------------------------
Address 17: Instruments Labels: 1K0-920-xxx-17.lbl
Part No: 1K0 920 953 D
Component: KOMBIINSTRUMENT 3HL 4312
Coding: 0022203
Shop #: WSC 08701 067 57207
VCID: 2C5759EF8F4BDC2165-8078
No fault code found.
-------------------------------------------------------------------------------
Address 19: CAN Gateway Labels: 1K0-907-530-V1.clb
Part No SW: 1K0 907 530 F HW: 1K0 907 951
Component: Gateway H10 0120
Revision: H10 Serial number: 28001061240324
Coding: 3D3F0B60071002
Shop #: WSC 00066 000 00000
VCID: 2A5B5FF785BFC21197-807E
1 Fault Found:
01304 - Radio
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 2
Fault Frequency: 42
Reset counter: 30
Mileage: 333098 km
Time Indication: 0
Date: 2000.00.00
Time: 10:46:57
-------------------------------------------------------------------------------
Address 25: Immobilizer Labels: 1K0-920-xxx-25.clb
Part No: 1K0 920 953 D
Component: IMMO 3HL 4312
Shop #: WSC 03200 444 55817
VCID: 2C5759EF8F4BDC2165-8078
No fault code found.
-------------------------------------------------------------------------------
Address 42: Door Elect, Driver Labels: 1K0-959-701-MIN2.lbl
Part No: 1K0 959 701 K
Component: Tuer-SG 024 2377
Coding: 0001269
Shop #: WSC 00066 000 00000
VCID: 36637B87410796F103-8062
No fault code found.
-------------------------------------------------------------------------------
Address 44: Steering Assist Labels: 1Kx-909-144-G2V2.clb
Part No: 1K1 909 144 K
Component: EPS_ZFLS Kl.5 D06 1701
Shop #: WSC 00000 000 00000
VCID: 33654293527583D924-8066
No fault code found.
-------------------------------------------------------------------------------
Address 46: Central Conv. Labels: 1K0-959-433-MIN.clb
Part No: 1K0 959 433 AF
Component: KSG 0401
Coding: 137803483F29058F880F048051A0
Shop #: WSC 00066 000 00000
VCID: 74E7818F17FBC4E1FD-8020
Subsystem 1 - Component: Sounder n.mounted
Subsystem 2 - Component: NGS n.mounted
Subsystem 3 - Component: IRUE n.mounted
No fault code found.
-------------------------------------------------------------------------------
Address 52: Door Elect, Pass. Labels: 1K0-959-702-MIN2.lbl
Part No: 1K0 959 702 K
Component: Tuer-SG 024 2377
Coding: 0001269
Shop #: WSC 00066 000 00000
VCID: 377D7683460D6FF918-8062
No fault code found.
-------------------------------------------------------------------------------
Address 56: Radio
Cannot be reached
-------------------------------------------------------------------------------
Address 62: Door, Rear Left Labels: 1K0-959-703-GEN2.lbl
Part No: 1K0 959 703 D
Component: Tuer-SG 021 2434
Coding: 0000144
Shop #: WSC 00066 000 00000
VCID: 3169489BA869B1C956-8064
No fault code found.
-------------------------------------------------------------------------------
Address 72: Door, Rear Right Labels: 1K0-959-704-GEN2.lbl
Part No: 1K0 959 704 D
Component: Tuer-SG 021 2434
Coding: 0000144
Shop #: WSC 00066 000 00000
VCID: 326B4797AD6F8AD12F-8066
No fault code found.
-------------------------------------------------------------------------------
Address 7D: Aux. Heat Labels: 1K0-963-235.lbl
Part No SW: 1K0 963 235 E HW: 1K0 963 235 E
Component: PTC-Element 0404
Revision: 00800000 Serial number:
Shop #: WSC 00000 000 00000
VCID: 2D5154EBB451D52972-8078
No fault code found.
End-------------------------(Elapsed Time: 01:43)--------------------------Thoughts? What can cause a code 12?
- Joined
- Jun 26, 2014
- Messages
- 1,436
- Reaction score
- 2,156
- Location
- Newcastle, England
- VCDS Serial number
- C?ID=24330
Hmm, 12 is usually a 'fleeting' code; it is a shut-off command from the ECU when it requires the engine to provide its highest power or torque. On my old Audi A4 (B5 8D model) you could only see code 12 during a log session when accelerating pretty hard.
On the old 'B5, before messages being sent over CAN; there was a dedicated pair of wires from the ECU to the HVAC head which sent this shutdown signal. It's worth checking what your setup uses with Wiring Diagrams and checking the integrity of those wires if you have them.
On the old 'B5, before messages being sent over CAN; there was a dedicated pair of wires from the ECU to the HVAC head which sent this shutdown signal. It's worth checking what your setup uses with Wiring Diagrams and checking the integrity of those wires if you have them.
Update:
Replaced the AC control panel in the dash with the Original one from the car - A/C Started working!
It initially threw a code for Low pressure, however I cleared that and it didnt come back.
I drove ~3 hours, mostly at highway speeds yesterday, with working AC. It was 75+ degrees outside.
Today, (55 degrees outside, Ohio right?) I took it back to the shop I have been working with, and they could not get the A/C to turn on. it is giving a constant Code of 299, Low Pressure. The Compressor Cutoff code is 3.
When I check it with VCDS, the Pressure Sensor is showing 0.0 bars, with the car off or running - doesn't matter. My research says that means absolute Vacuum? What would that point to?
Replaced the AC control panel in the dash with the Original one from the car - A/C Started working!
It initially threw a code for Low pressure, however I cleared that and it didnt come back.
I drove ~3 hours, mostly at highway speeds yesterday, with working AC. It was 75+ degrees outside.
Today, (55 degrees outside, Ohio right?) I took it back to the shop I have been working with, and they could not get the A/C to turn on. it is giving a constant Code of 299, Low Pressure. The Compressor Cutoff code is 3.
When I check it with VCDS, the Pressure Sensor is showing 0.0 bars, with the car off or running - doesn't matter. My research says that means absolute Vacuum? What would that point to?
"
2012 and newer Jetta sedans may have a customer concern of A/C shutting off when coming to a stop. When checking the HVAC controller for the Compressor Shut off code, [12- Shut-Off requested by Engine Control] maybe found, this is usually considered normal, the ECM is programmed to command the HVAC controller to shut off the compressor to allow increased engine rpm/vacuum when braking, mostly when the engine is cold, pre-catalyst operating temperature."
I have this problem on a 2012 jetta is it possible to code the 'shutting down' out? Thanks.
2012 and newer Jetta sedans may have a customer concern of A/C shutting off when coming to a stop. When checking the HVAC controller for the Compressor Shut off code, [12- Shut-Off requested by Engine Control] maybe found, this is usually considered normal, the ECM is programmed to command the HVAC controller to shut off the compressor to allow increased engine rpm/vacuum when braking, mostly when the engine is cold, pre-catalyst operating temperature."
I have this problem on a 2012 jetta is it possible to code the 'shutting down' out? Thanks.
- Joined
- Jan 29, 2014
- Messages
- 21,923
- Reaction score
- 9,319
- Location
- Montgomery, NY, USA
- VCDS Serial number
- C?ID=57337
Believe it or not a CAN com error or disruption from cluster or bad cluster on BUS can cause this and with no error especially if someone was handy with China Town tools!
In this case the radio is shooting a CAN error and because it tries to store and make a handshake for the cluster + PIN to authenticate it this may cause the issue.
Sometimes I run an isolated twisted pair from cluster to climate control and bam AC is back in business.
A flaky gateway can also cause this issue.
The more you know .........
In this case the radio is shooting a CAN error and because it tries to store and make a handshake for the cluster + PIN to authenticate it this may cause the issue.
Sometimes I run an isolated twisted pair from cluster to climate control and bam AC is back in business.
A flaky gateway can also cause this issue.
The more you know .........
Thanks for the reply but I did not make myself very clear this happens only for a few seconds at the time of braking unfortunately the ambient temperature is so high here that it makes a lot of difference.
Hello DrPeter, I hope you are well.
In a UK forum (Briskoda.net) the question came up recently of what a G65 sensor will read when the refrigerant is all gone (i.e. the system is at atmospheric pressure). My gut feeling was that this situation was consistent with what he was seeing - a MVB reading of 0.0 bar. The guy came back with the quote from your post here about expecting a 1 bar reading at atmospheric pressure.
"Important to note about the G65 sensor:
- A reading of 0.0 bar would indicate an absolute vacuum
- At Sea Level (atmospheric pressure) the typical reading is 1.0 bar"
I've just checked with a new sensor plugged into the loom connection of a known working system, and see a reading of 0.0 bar with the sensor in free air. So I think the above quote may not be right?
This page [http://www.vwgolf.org/checking_pressures-1515.html] seems to state similar things to what you've summarised, but I think it is actually saying that G65 reads positive/gauge pressure rather than absolute, because of the reference to agreement with the figures in the table, which are in 'positive pressure' scale?
What do you think?
Cheers,
Pete
In a UK forum (Briskoda.net) the question came up recently of what a G65 sensor will read when the refrigerant is all gone (i.e. the system is at atmospheric pressure). My gut feeling was that this situation was consistent with what he was seeing - a MVB reading of 0.0 bar. The guy came back with the quote from your post here about expecting a 1 bar reading at atmospheric pressure.
"Important to note about the G65 sensor:
- A reading of 0.0 bar would indicate an absolute vacuum
- At Sea Level (atmospheric pressure) the typical reading is 1.0 bar"
I've just checked with a new sensor plugged into the loom connection of a known working system, and see a reading of 0.0 bar with the sensor in free air. So I think the above quote may not be right?
This page [http://www.vwgolf.org/checking_pressures-1515.html] seems to state similar things to what you've summarised, but I think it is actually saying that G65 reads positive/gauge pressure rather than absolute, because of the reference to agreement with the figures in the table, which are in 'positive pressure' scale?
What do you think?
Cheers,
Pete
Good info here. My 2011 A4 problem was the G395 sensor too. Here’s what I saw:
Hard to believe the 0.0 absolute pressure. That’s a perfect vacuum. Especially after the Upper Limit Exceeded code earlier that day.
After I swapped for the new G395 (updated part is 4H0 959 126 B), my VCDS showed about 12.9 bar instead of the "ERROR" reading I'd gotten the last 2 days. But the AC button still wouldn't turn on, and I had different error, 03023 Running-in Requirement 005 - No or Incorrect Basic Setting / Adaptation. The good news is that I had a pressure reading.
I went into 08-Auto/HVAC>Basic Settings>Compressor Run-In/Cooling check. Then click ON/Run. Heard the compressor spin right up and the radiator fans spooled up...cold air from the dash. Took a minute of that before it said "Performed" and the HVAC shut off on the dash. Turned it back on at the dashboard and have had cold air now.
- AC light on console would not stay on
- No compressor, no cold air
- Got a code for G395 Upper Limit Exceeded - Intermittent 29.3 bar
- An hour later, I saw G395 Lower Limit Exceeded – 0.0 bar (absolute pressure)
- Later G395 codes just said ERROR
- Pin 1 I had continuity to ground
- Pin 2 saw 9+ volts with the motor running
- Pin 3 saw battery voltage with motor running.
Hard to believe the 0.0 absolute pressure. That’s a perfect vacuum. Especially after the Upper Limit Exceeded code earlier that day.
After I swapped for the new G395 (updated part is 4H0 959 126 B), my VCDS showed about 12.9 bar instead of the "ERROR" reading I'd gotten the last 2 days. But the AC button still wouldn't turn on, and I had different error, 03023 Running-in Requirement 005 - No or Incorrect Basic Setting / Adaptation. The good news is that I had a pressure reading.
I went into 08-Auto/HVAC>Basic Settings>Compressor Run-In/Cooling check. Then click ON/Run. Heard the compressor spin right up and the radiator fans spooled up...cold air from the dash. Took a minute of that before it said "Performed" and the HVAC shut off on the dash. Turned it back on at the dashboard and have had cold air now.
Last edited:
Hi all,
I have an issue with the AC of my 2012 2.5L Beetle. I am trying to narrow down where this might be coming from and I hope you guys can shed me some light. I got the car used over a year ago and the dealer confirmed it got Low Freon so they had to recharge it before passing State Inspection. When I was doing road test on the car, I experienced problems with the AC too but I did not think it is a problem. Symptoms are:
1. When starting the car in hot weather, it is slow for the AC to blow cold and it can blow Hot air for a while until the engine reaches around Operating Temp. Or this is at least how I feel it is doing.
2. The AC is manual so I always set it to the last level before Max A/C. It is blowing cold air (not super cold) but around 20C something or less when I injected a thermostat into the air vent. However, it can intermittently stop blowing cold air when driving on low RPM or stopping at a stop sign or stop-and-go traffic. You can feel that the fan is circulating only regular air through the vent making the cabin hotter. After a while, it resumes blowing cold air ==> Might it be because the compressor is freezing?
3. When driving on high-way or with Sports mode (high rpm), it blows cold air consistently.
4. I plugged a VagCom into my car. There there was a Meas Block on Engine called A/C Readiness and it always reported as Low. I have no idea what it means. Other than that, there are no other fault codes that I can find (confirming using Auto Scan)
I got my car AC checked at one of the Jiffy Lube place and the technician said my AC was fine although he said there was a missing cap on the Low or the High side.
I have Vag Com but I dont know what I should look into to confirm my issues. I also read the post here and I am not sure if my car is functioning by design. Does my car AC have a slow leak somewhere based on the information below?
"2012 and newer Jetta sedans may have a customer concern of A/C shutting off when coming to a stop. When checking the HVAC controller for the Compressor Shut off code, [12- Shut-Off requested by Engine Control] maybe found, this is usually considered normal, the ECM is programmed to command the HVAC controller to shut off the compressor to allow increased engine rpm/vacuum when braking, mostly when the engine is cold, pre-catalyst operating temperature."
Can it be due to the Compressor Regulator as described in here https://www.youtube.com/watch?v=94dR...index=17&t=0s?
I have an issue with the AC of my 2012 2.5L Beetle. I am trying to narrow down where this might be coming from and I hope you guys can shed me some light. I got the car used over a year ago and the dealer confirmed it got Low Freon so they had to recharge it before passing State Inspection. When I was doing road test on the car, I experienced problems with the AC too but I did not think it is a problem. Symptoms are:
1. When starting the car in hot weather, it is slow for the AC to blow cold and it can blow Hot air for a while until the engine reaches around Operating Temp. Or this is at least how I feel it is doing.
2. The AC is manual so I always set it to the last level before Max A/C. It is blowing cold air (not super cold) but around 20C something or less when I injected a thermostat into the air vent. However, it can intermittently stop blowing cold air when driving on low RPM or stopping at a stop sign or stop-and-go traffic. You can feel that the fan is circulating only regular air through the vent making the cabin hotter. After a while, it resumes blowing cold air ==> Might it be because the compressor is freezing?
3. When driving on high-way or with Sports mode (high rpm), it blows cold air consistently.
4. I plugged a VagCom into my car. There there was a Meas Block on Engine called A/C Readiness and it always reported as Low. I have no idea what it means. Other than that, there are no other fault codes that I can find (confirming using Auto Scan)
I got my car AC checked at one of the Jiffy Lube place and the technician said my AC was fine although he said there was a missing cap on the Low or the High side.
I have Vag Com but I dont know what I should look into to confirm my issues. I also read the post here and I am not sure if my car is functioning by design. Does my car AC have a slow leak somewhere based on the information below?
"2012 and newer Jetta sedans may have a customer concern of A/C shutting off when coming to a stop. When checking the HVAC controller for the Compressor Shut off code, [12- Shut-Off requested by Engine Control] maybe found, this is usually considered normal, the ECM is programmed to command the HVAC controller to shut off the compressor to allow increased engine rpm/vacuum when braking, mostly when the engine is cold, pre-catalyst operating temperature."
Can it be due to the Compressor Regulator as described in here https://www.youtube.com/watch?v=94dR...index=17&t=0s?
- Status