AC Fault

[ScottD3]

I had a mobile AC guy come to work to put some gas in my AC but before he gases it he does a diagnostic on the AC to make sure its not a waste of our time.

He went through the normal leak test and so on. It passed all of those test but when it came to testing the pump (turning it on), the pump never kicked in.
Checked for fault codes and nothing.

The guy said it could be a relay or a pump but we need to test them.

Anyone got any tips or advice on the best way to check the pump and relay and the location of the AC relay, is it an relay?

[mannyo]

I had mine done last year, it failed the leak test. However nearly two years on the AC is still working perfectly.

I am sure there would be fault codes for relay or the pump.

[snapdragon]

Dis you check for codes with VCDS, or did the AC man use something that they may not have shown up with. If it's not working, I'm sure there would be a fault in HVAC.

In VCDS> HVAC look in Supp. Codes to see what error codes are available to get an idea how comprehensive they are.

[ScottD3]

The guy used VCDS.
Only fault codes the low pressure fault which means no or low gas.
He put his gas in when testing for leaks and the fault code went away and never came back.

There was no other codes.

He had to drain the system when he went away.
I'm going to pop out tomorrow to see if I can get gassed up and do some more fault finding.
Not sure what.

[ainarssems]

Compressor should be running all the time on D3, not like the old cars with electric clutch so there will be no relay. There is just a solenoid valve that controls pressure and cooling dynamically rather than old style on/off and is more efficient way. My friend with A4 have been told similar thing like you by AC guy and told him AC compressor needs to be replaced at great cost.

I had a quick look, recommended him to replace pressure sensor, 35 mile drive later to closest Audi dealer who had 1 in stock, about £50 and 10 minutes later everything was working as it should. On the plus side he got free gas recharge as the AC guy did not take any money from him as it was not working after filling up.

[ScottD3]

Fitted a new pressure switch.

If it's constantly on, it's sounding more and more like a pump.

[ainarssems]

Just had a look and apparently there are both types of compressors used on D3 with electromagnetic clutch and permanently driven with pressure regulating valve so I guess you first need to find out which type of compressor you have.

If you have permanently on compressor without electromagnetic clutch you should not be running engine if the AC guy drained system, as compressor will not get lubricated properly and can get damaged or overheat.

[ScottD3]

It was drained about 1min from my house.
ECON modes go on instantly. I like to assume it turns the pump off so it's safer to drive.

The place to tomorrow is the other side of Plymouth. I'll get it gassed and see what happens.
At least i know it's not leaking.

I did an out put test on HVAC and the readings was going on and off.
I'll try and upload.

EDIT: https://youtu.be/8A57jG-GgCk

[ainarssems]

After watching your video I can tell that you have constantly driven compressor with pressure regulating valve N280. Compressors with electromagnetic clutch only show on/off in measuring blocks not load or duty cycle. Couple minute drive is probably OK as there will be some residual oil in the pump but I would not drive for more than couple of minutes.

Absolute pressure should be showing at least 2.6 bar when system is charged but engine not running, 4-29 bar when engine is running and AC switched on.
When the system is charged up load value in block 2 should be 0% with AC off, 30=100% with AC on, block 3 should be 12-20% with AC off and up to 87.5% with AC on.

[ScottD3]

Thanks Ainarssems for the information.

I just got back from getting the AC all gassed up and the ECON stayed off. WooHoo.
That's something.

I redid the videos of the output information.
First 20 seconds is with the engine off. The other 20 seconds is with the engine on. Enjoy the music selection. haha

https://youtu.be/Si1T-mEQk3M

Text version of the video.
Engine off
Block1 block2 block3 block4
0.715A 90% 27.5% 8.0

Engine on
Block1 block2 block3 block4
0.750A 80.5 27.5% 8.0
0.750A 80 25.5 7.2
0.750A 80.5 24.5 6.8