00819 - High Pressure Sensor (G65)
05-10-2016, 10:09 AM
#11
AudiWorld Super User
Thread Starter
Built a circuit and test the system - The N280 and compressor seemed
fine. Definitely the G65 8E0959126 or new 3R0959126. Just ordered an OEM from Europaparts instead of ECStuning (shipping is to high). Anyhow, hopefully it will get here before the weekend.
Now I can see how the system works with the 50hz 50% duty cycle circuit.
I'm glad that the compressor works. It's getting close!!!!
Cheers,
<a href="http://www.dognmonkey.com/audi/high-pressure-sensor-g65-ac-blows-hot-air.html">Louis</a>
Now I can see how the system works with the 50hz 50% duty cycle circuit.
I'm glad that the compressor works. It's getting close!!!!
Cheers,
<a href="http://www.dognmonkey.com/audi/high-pressure-sensor-g65-ac-blows-hot-air.html">Louis</a>
05-12-2016, 08:29 PM
#13
AudiWorld Super User
Thread Starter
Yes, it's fixed...
It's the power of believing in Audi Engineering (8 year old Q7@47k miles - 1 set of tires - nothing else even original brakes - 10 year old A8L @ 115k miles- 1 -set of tires - brakes and oil). The compressor is not bad regardless on how Mickey Mouse I charged the system. The system is so well protected with great Control System that protects the heart of the system, the ECU and all the sensor G65 and N280.
Ok, the G65 3R0959126 is only a PWM and a pressure sensor, so anyone can build it, therefore, I got the OEM which is less than 1/2 of the original one. $39 + o-ring and shipping=$46 in 3 days, amazing.
So, if the 00819 - High Pressure Sensor (G65) is intermittent or on the way out, some days you will have cold air, and some days you don't and one day, it just leaks or dead and won't turn on the N280 anymore, then that's the day you replace it, in my case.
It's also a good idea is to build a $10 mini board 50hz, 50% duty cycle to check your AC compressor regardless if you're not sure if your sensor is bad.
I do believe Audi build great cars with extreme engineering regardless on how people complain. Yes, some designs may be NOT as robust as the technical would say or intuitive, but the quality of the products is superior IMHO.
I'm glad I got this problem, now I learned so much about AC system, especially with Audi.
Thanks all for great advice and troubleshooting techniques.
Hopefully, this thread will help a few people with 00819 - High Pressure Sensor (G65) and like I always believe "never think of the worst case scenario, investigate the problem and the simplest thing can be the culprit, but we do have to study to understand system and troubleshoot logically.
Cheers,
<a href="http://www.dognmonkey.com/audi/high-pressure-sensor-g65-ac-blows-hot-air.html">Louis</a>
Ok, the G65 3R0959126 is only a PWM and a pressure sensor, so anyone can build it, therefore, I got the OEM which is less than 1/2 of the original one. $39 + o-ring and shipping=$46 in 3 days, amazing.
So, if the 00819 - High Pressure Sensor (G65) is intermittent or on the way out, some days you will have cold air, and some days you don't and one day, it just leaks or dead and won't turn on the N280 anymore, then that's the day you replace it, in my case.
It's also a good idea is to build a $10 mini board 50hz, 50% duty cycle to check your AC compressor regardless if you're not sure if your sensor is bad.
I do believe Audi build great cars with extreme engineering regardless on how people complain. Yes, some designs may be NOT as robust as the technical would say or intuitive, but the quality of the products is superior IMHO.
I'm glad I got this problem, now I learned so much about AC system, especially with Audi.
Thanks all for great advice and troubleshooting techniques.
Hopefully, this thread will help a few people with 00819 - High Pressure Sensor (G65) and like I always believe "never think of the worst case scenario, investigate the problem and the simplest thing can be the culprit, but we do have to study to understand system and troubleshoot logically.
Cheers,
<a href="http://www.dognmonkey.com/audi/high-pressure-sensor-g65-ac-blows-hot-air.html">Louis</a>
Last edited by ltooz_a6_a8_q7; 05-12-2016 at 08:33 PM.
05-13-2016, 05:25 PM
#16
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I might try this as my a/c has been working intermittently for the past few months. Sometimes it would blow cold and other times the a/c wouldnt blow as cold, usually on really hot days. Only fault codes are for 00819 G65 high pressure sensor and one for n280 compressor regulator, which I now believe is caused by the faulty high pressure sensor. Going to order one today and post the results. Hopefully it would be as good as Louis's results because I highly doubt a bad compressor because when there is cold air, it usually is VERY cold. Let's see....
Last edited by Junius; 05-13-2016 at 05:28 PM.
05-18-2016, 09:19 AM
#17
AudiWorld Super User
Thread Starter
Final Videos... Conclusions
Remove the bumper cover with the left bottom nut - need to remove the fog light assembly to access, unless someone knows another way that's better. The last guy didn't put back the nut.
Release the serpentine belt tension using 19mm socket or box wrench - Mine didn't move a lot, just enough to wiggle the belt out, something is stuck or that's the design or I missed something.
- Audi A8 D3 AC system: As I understand while having this experience, the AC system blows cold or hot air whenever it feels like last few months and it's totally out, the ECON settings was forced to ON = AC OFF. G65 High Pressure Sensor 8E0959126 (old part#) 3R0959126 (new part #) sensed the pressure and tells the N280 pressure regulator NOT to turn on. According to ElsaWin, if the waveform on the G65 is over 87% duty cycle, the Freon pressure is too low and under 12% duty cycle, the Freon pressure is too high. G65 is just a Pressure PWM (pulse width modulator) sensor, so after market ones should do $39 vs $89-105 from dealer. If you can set the ECON to OFF (AC ON) at AUTO setting, you have enough FREON to run.
- VCDS will show 00819-High Pressure Sensor (G65) - sometimes "lower limit" and sometimes "upper limit" whichever the case, the AC won't kick on.
- If you don't have a VCDS, buy an AC manifold set from harbor freight or <a href="http://amzn.to/1TovyvZ">amazon for $44-55</a> and you can check without any problems:
a. If the AC has Freon and the N280 is turned OFF by G65 sensor: low side pressure is high (60-80) but the high side (RED) is steady at the same pressure as low side (60-80).
b. If the AC has Freon and the N280 is turned ON (system is working) by G65 sensor: low side pressure will decrease (30-40) while high side (RED) is increasing above 100-200.
- If you have a leaking G65 like mine, when you hook up the AC manifold, the low side and high side will have 0 pressure - the system is empty. While it's empty, you can get an air vacuum from harbor freight for $19 to check for leaks, providing you have a 120PSI compressor at home. If NOT, you can go to the AC shop and they can check it for you - $80 minimum. It will take more than an hour to verify if the system is leaking.
- The best is to build a simple <a href="http://www.electronics-tutorials.ws/waveforms/555_oscillator.html" target="_blank">50hz 50% duty cycle circuit</a> to check the AC compressor and the electronic system - by bypassing the sensor, simulate the correct pressure signals to the ECU for it to turn on the N280 because sometimes, the new pressure sensor can be DEFECTIVE (since it's electronic circuit) and won't turn on the N280 even you replace it.
To me, Audi has bad reputation for reliability because of their complex control system (overly designed but I think it's great) - People who work on them don't understand the system and start to shotgun (replace without educated information or guess) parts until they get the right one on customers' expense. The myth of blowing up the AC compressor due to overcharging the Freon - Yes, it's good to have gauges and correct information of the AC Freon capacity - I couldn't find any sticker on my car that shows how much Freon is needed for my 4.2L - TSHong owns a shop and the specs he quoted was 21.2 oz +/- 1.8 oz, so maximum we can charge is 2-12oz cans. To me, even with 1-12oz can from empty system, it's already cold.
I like to do things at home, I hate going to the shop and wait and worry someone will screw up my car (every time I open something, something is missing because the people before didn't do it right), it's not the money... Really.
Cheers,
<a href="http://www.dognmonkey.com/audi/high-pressure-sensor-g65-ac-blows-hot-air.html">Louis</a>
- Audi A8 D3 AC system: As I understand while having this experience, the AC system blows cold or hot air whenever it feels like last few months and it's totally out, the ECON settings was forced to ON = AC OFF. G65 High Pressure Sensor 8E0959126 (old part#) 3R0959126 (new part #) sensed the pressure and tells the N280 pressure regulator NOT to turn on. According to ElsaWin, if the waveform on the G65 is over 87% duty cycle, the Freon pressure is too low and under 12% duty cycle, the Freon pressure is too high. G65 is just a Pressure PWM (pulse width modulator) sensor, so after market ones should do $39 vs $89-105 from dealer. If you can set the ECON to OFF (AC ON) at AUTO setting, you have enough FREON to run.
- VCDS will show 00819-High Pressure Sensor (G65) - sometimes "lower limit" and sometimes "upper limit" whichever the case, the AC won't kick on.
- If you don't have a VCDS, buy an AC manifold set from harbor freight or <a href="http://amzn.to/1TovyvZ">amazon for $44-55</a> and you can check without any problems:
a. If the AC has Freon and the N280 is turned OFF by G65 sensor: low side pressure is high (60-80) but the high side (RED) is steady at the same pressure as low side (60-80).
b. If the AC has Freon and the N280 is turned ON (system is working) by G65 sensor: low side pressure will decrease (30-40) while high side (RED) is increasing above 100-200.
- If you have a leaking G65 like mine, when you hook up the AC manifold, the low side and high side will have 0 pressure - the system is empty. While it's empty, you can get an air vacuum from harbor freight for $19 to check for leaks, providing you have a 120PSI compressor at home. If NOT, you can go to the AC shop and they can check it for you - $80 minimum. It will take more than an hour to verify if the system is leaking.
- The best is to build a simple <a href="http://www.electronics-tutorials.ws/waveforms/555_oscillator.html" target="_blank">50hz 50% duty cycle circuit</a> to check the AC compressor and the electronic system - by bypassing the sensor, simulate the correct pressure signals to the ECU for it to turn on the N280 because sometimes, the new pressure sensor can be DEFECTIVE (since it's electronic circuit) and won't turn on the N280 even you replace it.
To me, Audi has bad reputation for reliability because of their complex control system (overly designed but I think it's great) - People who work on them don't understand the system and start to shotgun (replace without educated information or guess) parts until they get the right one on customers' expense. The myth of blowing up the AC compressor due to overcharging the Freon - Yes, it's good to have gauges and correct information of the AC Freon capacity - I couldn't find any sticker on my car that shows how much Freon is needed for my 4.2L - TSHong owns a shop and the specs he quoted was 21.2 oz +/- 1.8 oz, so maximum we can charge is 2-12oz cans. To me, even with 1-12oz can from empty system, it's already cold.
I like to do things at home, I hate going to the shop and wait and worry someone will screw up my car (every time I open something, something is missing because the people before didn't do it right), it's not the money... Really.
Cheers,
<a href="http://www.dognmonkey.com/audi/high-pressure-sensor-g65-ac-blows-hot-air.html">Louis</a>
Last edited by ltooz_a6_a8_q7; 05-18-2016 at 12:26 PM.
06-04-2019, 01:59 PM
#18
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06-04-2019, 02:25 PM
#19
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Ac
I tried also everything! Regas with freon! New ac presure sensor! I tested the air compressor with vcds and is working! Last try is to change the climate control! The ECON on mine is not stuck! If I put the ECON OFF ( Ac ON ) air compressor still not start! Don't have any idea what could be! Have 3 day of trying to figure out! Any advice would be much appreciated! Thanks
06-04-2019, 02:48 PM
#20
AudiWorld Super User
Thread Starter
I tried also everything! Regas with freon! New ac presure sensor! I tested the air compressor with vcds and is working! Last try is to change the climate control! The ECON on mine is not stuck! If I put the ECON OFF ( Ac ON ) air compressor still not start! Don't have any idea what could be! Have 3 day of trying to figure out! Any advice would be much appreciated! Thanks
Cheers,
Louis