Weird Running Problem?

reptor245

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hey guys, i noticed today that when i press the air con button on my A3 1.8T (1999) the engine cuts out. havent run the Vag-com yet but has anyone any ideas whats going on?
 
yeah i thought that. ive just drove home with the lights on, the radio and and heater on.

it has got these fault codes tho, not sure if thats got anything to do with this problem.

VAG-COM Version: Release 409.1-S

Chassis Type: 8L - Audi A3/S3
Scan: 01,02,03,08,15,17,22,35,37,45,54,55,56

-------------------------------------------------------------------------------
Address 01: Engine
Controller: 06A 906 018 CJ
Component: 1.8L R4/5VT MOTR HS D01
Coding: 04000
Shop #: WSC 06435
2 Faults Found:
18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 - - - Intermittent
16500 - Shareware Version. To Decode all DTCs
P0116 - 35-10 - Please Register/Activate - Intermittent
Readiness: N/A
-------------------------------------------------------------------------------
Address 03: ABS Brakes
Controller: 1J0 907 379 Q
Component: ABS/EDS 20 IE CAN 0001
Coding: 13504
Shop #: WSC 06435
1 Fault Found:
01276 - ABS Hydraulic Pump (V64)
16-10 - Signal Outside Specifications - Intermittent
 
yeah i will check that tmr. it has gone into limp mode twice today too.. very anoying.
 
Battery, Alternator, or a coroded earth perhaps. As an extra test to that suggested above, turn-on the heated rear window (with all the other stuff turned on too) - that generally draws a decent bit of load (see if interior lights/headlights dim a little when you hit the button).

You can check with VAG-COM (it'll be in a few groups of measured value blocks in address 01 - Engine) or a multimeter, but check you're getting 14V across the battery with the engine running. If you're not, it's almost definitely one of the above; and the alternator high on the list of suspects at that point; but how old is the battery on the car? Is it a maintenance free one or does it have top-up ports? Give the Alternator belt a quick visual check (doesn't look split anywhere around its outside (as far as you can see), and that it appears fairly tight/not slipping).

If you are getting a good 14V with the engine running, it's going to be something else - but I wouldn't like to say what - I wonder if the air-con compressor (if failed) could put enough load on the engine to cause it to cut out? Dunno exactly how it's driven on your car, so I'd check voltages first while someone more familar with 8L air-con setup scratches their head some more...

Let us know how you get on,

Regards,

Rob.
 
Thanks rob for the detailed info :)
the battery was put on the car the day i bought it. (2yrs ago) seems a little odd tho how its gone into limp mode a couple of times today, even without me pressing the A/C button. basicly the car was fine, then i had some brakes fitted and noticed there abit of smoke coming from them when hot (guess it was just grease on the disks) then today its gone into limp mode 3 times, when i press the A/C button it cuts out. the engine revs up alittle like normal when i press it, then it just dies. im confused as i ran Vag-Com and it only came up with the 2 fault codes. altho to be fair it came up with them yesturday before i noticed the A/C issue. As stated before, you guys think it might be just a loose battery connection? ive checked the fuses and the ones on the battery and they all seem fine. its worrying ..arrrhhhhh
 
I think it's likely to be coincidence with the other stuff that's going on (brakes etc. - but I'd keep an eye on that smoking situation!), although I imagine limp mode might be connected to power supply shortages. Honestly the first thing I'd be checking is the voltage with the engine running. Loose/corroded connections are a possibility, but if nothing's been changed/moved with them it's less likely they'd cause an issue.

A two year old battery could well be on its way out (companies like to say they'll last for a gazillion years these days, but in my experience its not the case), so it might just be that; again checking voltage across the battery (with a multimeter) or having a look at voltages with VAG-COM while the engine running helps to rule things out (primarily the Alternator) - if doubts are raised about the battery, get down to Halfords and they'll drop test it for you (show an interest in the readings on their meter though, don't want them to say it's goosed if it's not) - and then when they offer to charge you £80-£120 for a new one, politely decline and get down to a scrappy where you'll get one for £20 - just pick a good one!

The Terminal 30 DTC is very common, and related to low power supply, but that could've been in there for years (unless you're certain it's a new appearance). It could be another sign that the battery's on its way out (unless it's been very low after the car has stood for a long time without use - but that in itself doesn't do a battery much good)...

Regards,

Rob.
 
just an update. i think its the air con compressor thats fecked. ive noticed when i press the air con button and put more revs on to keep the engine running, theres a loud squeel. does anyone have one for sale?
 

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