Aircon not working when I bought car, had system recharged before the VCDS arrived, it had pressure and was evacuated, refilled but aircon still not functioning due to G65 fault code unknown at that time, I do not know for sure if the system still has pressure now a month later.

 

VCDS diagnosed code 819 G65 open or short to ground, replaced it with a very cheap Chinese one, perhaps a mistake.

 

With new sensor fitted VCDS still throws up the same code after resetting, looking at the measuring blocks it does not show a value for the G65 pressure just a dash (-) where the value should be, I have checked the wiring and the 12v and ground connections are OK, I sold my O scope so am relying on VCDS to do the measuring.

 

My questions:

 

With a functioning G65 connected and no wiring faults, if it is left hanging in fresh air would it show no fault code but zero pressure or 1 bar in the measuring blocks? If so then I conclude that the cheapy sensor is no good;

 

Secondly with a good sensor fitted and installed in the A/C line, no wiring faults, would it throw up a G65 code if the system had no pressure or would it just indicate this in the measuring blocks?

 

Thank you

Good sensor in fresh air with working electronic system will read 0 bar in measuring blocks.

0 bar in the system will cause a low pressure fault code.

 

Checked fuses yet? Sorry, I must've been on autopilot, if you have 12V at the sensor the fuse must be intact.

Edited 14 October, 20187 yr by Wino
Correction

Thanks, thats what I had surmised.

 

So either the cheap switch is faulty or possibly a wiring/connector fault from the signal wire to whatever module it goes to.

 

Have ordered a not quite so cheap sensor from Germany where they have sold 430 of them with good reviews and will see what it does.

 

Something seems to have happened to the connector with all the clipping and unclipping on the old and new sensors, it now takes a lot of force to push it on hard enough for the lock pawl to engage making it vety hard to remove, its back on the installed sensor but with the tight access its going to be real hard to remove it next time, if I remove the purple coloured C clip from inside the connector it engages as it did before yet the inanrds dont fall out, checked it over with a magnifying glass and cant see anything wrong, its the same on both sensors but I'm sure is making good electrical contact.

 

Where does the signal wire lead to at the other end? - A fan control module? where is it located? - I can be checking that out while waiting for the new switch.

The output signal from the G65 sensor goes straight to the HVAC module on the Mk2, rather than the fan control module.

Purple/yellow wire to pin 5 of a black 20-way connector if you have the Climatic system, pin 2 if you have Climatronic.

How / what did you solve your problem. I have the exact same problem. I have changed the G65 sensor two times ( new, non OEM sensors) And the Hvac unit but still the same 00819 - open or short to ground code. 

I have tested the +/- to the sensor, all good there. I have checked the wiring between sensor and Hvac unit and its all good. HELP plz I am running out of ideas now

 

 

Why does my Yeti blow warm air when the air con is set on low, it takes ages to go cold but when it does go cold it's lovely and cold , but then blows warm air for a while then back to cold. I've had the gas topped up so that's ok.

There is a flap that mixes hot & cold air that is servo controlled - I would get a fault code scan done which will show if there is a problem with this temperature control flap.

Well, after five years, maybe some of you have explanation for this problem.

 

I have same problem, AC not working, removed old sensor, inspected it - it was full of oil and chip on the sensor was burned, that was also the cause of losing refrigerant over the years.

 

I bought new sensor from Aliexpress (99% things I bought from there was functional), after that I checked with VCDS and got same G65 pressure sensor short to ground, after that i started to have suspicions about that chinese sensor and bought new one in big european spare parts shop, the outcome is the same. Next thing I did was buying new climatronic(used but like new, instead of old and worn) because I was thinking that maybe the input on pcb was dead because of burned sensor.

 

I have measured all the lines, sensor is powered with 12V, even I did direct connections from sensor in my hand to the climatronic unit with new wires but still everything is the same. It is started to be frustrating and I dont have a clue yet. 

 

 

Well, everything solved. Problem was in the new sensor which is said to be compatible and is not OEM - sensor KTT130000.

 

On osciloscope its showing good voltage out readings and pwm shape, when it is connected on longer wire it drops down, its signal power is probably less than on original sensor, and due to not perfect resistance on climatronic input, it drops down.

 

When sensor connected in cabin, on 20cm wire, powered from 12V lighter there is no fault any more.

 

In the end I used NE555 timer chip tuned on 50Hz and 70% PWM and AC is working, ofcourse this is dangerous if you dont know what are the pressures in the system, this is until i buy new sensor.

 

I hope this helps someone.