Hi all,


Come to use the Air conditioner on full cool today and found it doesn't work. I put a temp probe into the middle vent and its 28 deg c when the outside temp is only 22 deg So its cooler to turn the blower off completely and open the windows.


I've put a VAS on the car and it only had one intermittent fault which was compressor pressure sensor intermittent fault. Ive cleared it and there are no more faults showing after hours of driving.


Refrigerant pressure is 4 bar.


how do you know if your running out of refrigerant??


Thanks
fRank

 

I know this video is not a Bentley, but it will show you the equipment necessary and the principles involved.

 

Thanks for that, I was hoping some one like Bentleytech would come on and explain if my VAS 5054a computer should tell me if the refrigerant level was low ?? All I could see was pressure sensor reading of 4 bar ??
Frank

 

hi,yes the vas should tell you if you have refrigerant loss,once that code appears the compressor will not come on until issue rectified,have you run car with gauges on,if you have what is the low pressure and what is the high at idle and what happens on acceleration. being that you had a code for compressor pressure you may have a compressor that is done. if that is the case do not just replace it the system will need flushing and a new expansion valve which on the GT is a tube type. we did also experience issues with the high pressure switches.just as note if there is a code in the ac control module..9 times out of ten it will shut down the system.all codes will need clearing for the compressor to kick in.

 

Thanks Mate,
Unfortunately I only have a VAS, I come from the Rally world where air con isn't fitted so I've never worked on or even studied Air-conditioning. The only pressure readings is with the diagnostic function on the VAS which gives sensors and pressure readouts. The only pressure readout was giving 4 bar.

 

i would clear the code and see if you can get compressor to kick in, the best thing is you really need gauges to see what is going on, there are many components that could cause no air con.

 

Thanks, been playing around but cant find the issue. Car goes onto Bently next Wednesday.

 

I actually got a code today
00229 02
Pressure below lower limit ??


Any advice please?


Fank

 

Check this thread, D3 A8/Phaeton and CGT's share a lot of parts. http://forums.quattroworld.com/a8d3/msgs/10305.phtml

 

Cheers

 

Sorry to revive an old thread. Any help would be appreciated:

My CGT has a problem where the A/C will suddenly go out (blower still blows but seems like the compressor cut out). I don't think it's refrigerant because if I put the car away and come back to it a few hours or a day later, the A/C works again no problem with cold air. I can go days sometimes weeks without issue, but occasionally the A/C would stop working again.

Could this be a problem with the compressor pressure sensor transducer? This is the air conditioning pressure sensor fitted to the A/C hose from the condensor to compressor. I've had a look at the threads about the flap motors going bad, but mine seems to still be able to alternate between the two modes just that the air is no longer being cooled but I can hear some flap movements when I press the button so I don't think it's the flaps.

 

Before over spending on this one. Have an automotive AC service company with an AC manifold pressure gauge check your high and low pressure. Without doing this there is no clear diagnosis.

 

Turned out it was a compressor. They did the belts and some pulleys while they were in there. And they happened to snap my bumper in half too (apparently CGT and FS bumpers plastic are prone to cracking with age??). It burned a hole in my wallet for sure.

Now the A/C works but it's still not ice cold. They then replaced the restrictor valve and that made it better, but now the problem is back. Wonder if it's worth changing the restrictor valve again - as I heard debris can kill them - so maybe there was some leftover debris still in the system? Thoughts before I throw more money at this car.

I'm getting the flap motor code too, but not sure if that has anything to do with it. I thought it only affects whether I can recirculate the air when it stinks outside - but please correct me if I'm wrong.

 

A couple things catch my attention. The receiver drier should have been replaced. Some of the debris is captured there and because it is a condensate trap as well normally with compressor replacement it gets changed. After compressor failure compressed nitrogen needs to be passed through the system to expel debris. Additionally a permanent inline filter is installed to catch any residual debris. Again a high and low pressure reading needs to be taken to see what's going on.

This is standard operating procedure on automotive HVAC.

 

They replaced the receiver driver (the thing that looks like a thermos) and they said they cleared out the system though I don't know using what. They've recommended I change the flap motors since they saw a fault code for them. Just hope that's correct.