I am looking for a wiring diagram (Specifically for the a/c) 2005 Bentley Continental GT. I just purchase her from friend and the a/c compressor will not engage. The Aux battery needed to be replaced so I did so thinking this may be an issue since the a/c did work fine about a week before I picked it up. I checked the pressure and it was equalized at about 120 psi. I could be wrong but I am thinking it may be a relay or something else in the electrical system. Does anyone have a recommendation for a good source for a wiring diagram?

 

By the way 120 PSI static pressure is too high. Depending on ambient temperature the static pressure should be more or less 40 (+)psi. Always good to evaluate the electronics. However the pressure is suspect. The Bentley AC module made interrupt operation based on this pressure. Be careful not to permanently hurt the system without verifying my suspicion.

 

Hello @1eapplebaum ,
Sorry, but I disagree with the static pressure of 40ish psi, maybe in a winter freeze and a cold engine 😜

The static pressure of 100-120 is normal, ofcourse depending on ambient temperature as you stated, even more so if the engine is hot, if the engine is cold and cool weather, then you may see 80 psi static pressure, the low side operating pressure would be around 35psi to 40 psi, while the high side would range between 175 to 200 psi, so one could never have a static as low as 40, that would be an under charged system on a 2005 134A system.

A video by Louis over at AW.

Johnny

 

Hi JH,

Yes, your explanation makes sense. I was confusing "operating" low pressure side reading. Also we don't know if the vehicle had been running in the hot Texas sun 😓 when the static pressure was measured?

 

Agreed, outside temperature and engine temperature make a difference, I recently had an AC issue also, and still do, I drove from NJ to Newport RI and the AC was nice and cold, very cold, but on the return trip home the AC went out, it was a disgusting 90°+ humid rainy ride home...

Upon arriving home I put the gauges on and had 110 static psi on a semi cooled down engine, I then went to my friends shop and used his recovery machine to evacuate the system, I pulled out 1.44 pounds / 653 grams /23.04 oz, the system holds 650 with a +/- of 20 grams, so I vacuumed the system and refilled with 1.47 pounds / 666.78 grams / 23.52 oz, with this fill on a 93° day and a hot engine, my static pressure reading was just at 120 psi, but I still have no AC, using my Ross-Tech VCDS I am able to go into the HVAC control and run through the output tests to activate the compressor, test shows that it is active but the bar readings only vary a miniscule amount, and the return line (low pressure) does not get cold at all, so the compressor is not working properly, and to think that I sold the compressors I had...

What is really annoying is that this compressor only has 11,000 +/- miles on it, and it fails, plus a few on here have had the same, yet my 2005 A8L W12 with over 200,000 mile is on the original compressor, I am curious to see how many miles are on @Ole Man GT 's 05.

Johnny

 

Thanks for the Flying Spares tip. It is on order and on the way. I did check fuses and they were all good.

Source

 

The engine was warm and it was about 95 when I through the gauges on. 120 did not seem unreasonable under these conditions. Of course it is possible I have a compressor issue but the car was a one owner with 18,000 original miles on it so I did not really factor that in. Hopefully when my wiring diagram comes in I can rule out any electrical issues before I start looking at a compressor replacement. I am sure that may be a little pricey.

 

Hey Ole Man GT,

Do you have access a vag-com unit? Have you already checked for fault codes?

if not, you might be able to narrow down a bit, depending on the root cause. (Pressure sensor, indicated pressure, flapper motors, cooling fan, basic settings not performed, solenoid/whatever, etc.)

If the Bentley system is anything like Audis of the era, One piece of advice I would have though is NOT to run the basic settings if you have a flapper motor error (or any other complex root cause repair, if you are doing diy), as the unit will default to an ECON mode and you will not be able to turn on the compressor until the problem is fixed (or subsequently has a huge number of no error cycles, somewhere well north of 150 cycles, as I recall) and it passes all of the basic settings requirements and basic settings are established. On the Audis these flapper motors are buried deep in the dash and an extremely laborious undertaking, requiring a lot of awkward positions to reach things. Not sure, but, I suspect it’s similar for Bentley, though some flapper motors may be easier to reach than others, depending on location.

For the Audi I had issues with, if basic settings are not attempted/failed, the unit can still turn on, just will have a persistent flapper motor error code, until resolved. It will need to be addressed eventually, but you won’t be forced to make the time right now, if you are “DIY” ing

There’s great help at the Ross-tech forum and Uwe, the resident expert and others on the forum are usually very responsive. That alone is worth getting the Ross-tech version to me.

If you have a basic settings not performed error, it likely means the folks who had your car tried to clear an error code, ran the basic settings based on internet advice, and locked up the system, but your ac would be stuck in Econ mode. Not sure if you can tell on Bentley, but the audis have a little Econ led on the on/off buttons.

 

It does have an LED for ECON but it is not illuminated. I have a Ross-Tech but have not review their forum, thanks for that advice. I have a lot to learn about this system.
The long story is the a/c was working the week before I picked it up. Driving home I was getting a low bat indicator for the aux battery. I assumed this could cause the a/c to not engage as I had read that on this forum. Replaced the aux battery and looked at the codes and there were quite a few present. A lot of short to grounds or opens. The only a/c codes were lower limit exceeded, door control module no signal and loss of refrigerant.
I cleared the codes and drove around for about an hour and pulled the codes again. I did have a few codes return.
Engine code 18331 please check DTC memory of ECU 2. I am not quite sure yet how to check this.
Pass seat, 01312 Powertrain data bus
Cent electric, excessive comm errors.
Seat Mem. Drvr, 6 fault codes all No or Incorrect Basic setting.
Navigating, excessive comm errors
Battery Charger, 00003 control module, 014 defective.

I am currently attempting to DIY this issue.

 

Thank you @sam08861 , I will not be doing the basic setting... 😀

​​​​​​Hello @Ole Man GT ,
To check "ECU 2" go to drivetrain and click on 11- engine II as shown below.

As far as the AC, go into HVAC and select output test, click activate to to start the procedure, just click the first test, which is activation of the compressors N280 pressure valve, when you are done testing the N280, just hit done go back, no need to do the very long test procedure if you do not want to, and as these compressors have no clutch (just an FYI in case you were wondering) there is no relay for the activation of any clutch, the N280 pressure valve works by way of voltage between 4 to 12 volts to regulate pressure, while I had my gauges on the vehicle Wednesday I observed that the pressures were around 140psi static (engine off), it was hot in the blazing sun and a hot engine, phone said it was 97° out, but the car said it was 103°, so I brought the gauges into the driver's seat, started the engine, and lightly applied my foot to the throttle to about 700 rpm the low pressure side started to drop to 110, the high side was climbing to 160, if I raised the RPM to 850 I got to 102 low side, and 175ish high side, but then it would cut out and all pressures would go back to almost equal until I let off the throttle and started over, the pressures reacted the same each time, and the suction (low) line actually got cooler to the touch, and I would get a brief second of cooler air out the vents, the system reacted the same exact way when using the output test to activate the N280 valve, only difference is that the test puts the blower motor at very low speed if not off during the test, so when you end the test and the blower comes back on, you get a little longer but brief moment of cool air.

So, I will either later today or tomorrow test the N280 valve on the vehicle by feeding it 12 volts to send it to full closed position for max duty, I may do it a few times to listen for the clicking of the solenoid to maybe free it up, I will also measure the voltage to the valve from the control module.

Johnny


.

 

I too am having this same issue with my 05 Continental Gt, one day the ac was blowing chilling cold.. got out the car and went in the store. When I came back out it stopped blowing cold and hasn't been back on. Out of NOWHERE!