Now baffled and stuck.......

S3Zek

S3Zek

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Right here's where I now stand. On last Friday went to go shopping for food, pulled into supermarket car park after being in a small amount of traffic parked up and before I turned it off big beep and temp at 120ish on gauge,

NICE.....just what I wanted, air con has also given up the ghost a week ago before that plus my elictric water pump and the alternater went this week.
So I've spent most of the week reading all the stickys and google but to no aval as everyone seems to end the post with a fuse, regass, control mod or fan.
Stuck a spair alternator on so that's sorted.
But both fans work well when powered up, water pump dose the same, air con has been regassed just to make sure, fitted new control mod from Audi, all fueses are good but cleaned them anyway plus all the track for them,
Nothing......
the clutch won't engauge on the air con, but seems to have 12v to it when keys are out? It this right?
Tried bridging the two stage fan switch plug when the cars on to see if they would come on but nothing again and there is no power to the plug ether, is this also right?
My laptop is nackered so I can't use my vcds.
Is there anything before the control mod that can cause all this?
If anyone has vcds near and wants to earn a few drinks it would be much appreciated. :(
 
Have you powered the a/c pump directly? Does the clutch kit in? Have you tested the a/c low pressure switch? Cause if I'm not mistaken if the low pressure switch is faulty then it is basically telling the a/c it doesn't have enough pressure in the system so it won't engage the pump, to protect the pump basically.
 
waterpump could well of gone or if your'e lucky thermostat. Either way i would whip the thermostat out and if you stick your fingers in you can feel if the waterpump is ok, they normally break apart. Mine did this without any warning.
 
Temp stays good under normal condishions, water pump and cambelt done 6 months ago and the I changed the thermostat 3weeks ago, the fans just don't come on ever or with the ac. I haven't stuck 12v to the ac pump as it had 12v at the plug but will try direct feed to it tomo. Where is the pressure switch located?
 
Can't remember for sure, but look at the a/c pipes and look for a switch with a 2 pin plug on it, it's in the engine bay and if memory serves its towards the front behind the fans, just unplug it and test the switch. I can have a look at mine in the morning to confirm if that helps? Sorry to sound vague but its been awhile since I last did one!!
 
Had it drained and regassed anyhow too
 
System can be full dude, but I'd the low pressure switch is faulty then it will just think the system is empty and won't fire in the pump!
 
Thanks mate will look for that tomo.
 
Also before the ac gave up the ghost it worked for about 5-10 mins then would shut its self off, would turn it back on then it would do the same, then it just got to the point where if you turned it on the chutch would engage then disengage so on and so on, then it just stoped all together,
 
But I don't know how long the fans haven't been working.
 
I reckon it is your low pressure sensor, did they check yours system for leaks when it was re gassed? Sadly dude when you change the switch, should it be at fault youll need a de-gas and re-gas again! If they didn't before, get it checked for leaks!
 
A/c fan won't cut in if the a/c isnt on. So I think you'll find soon as your a/c works the puller fan should start to work again!
 
It had about 110psi one side and a 100psi the other and 350 out of 750 of the gas when hook up before it was sucked out and I haven't touched it since I've had it over 3 1/2 year lol,
I never payed as it didn't fix the prob so I will have them pump it out again for the switch. If I test the switch and it works, where do I go from there?
 
If the switch isn't faulty it could possibly be the climate control unit itself (the dash mounted one) perhaps the switch is playing up in that, but my money is on the low pressure switch, was 750 the correct amount to put back in? Cause also to much is a problem also!
 
You may still have the sticker under your bonnet stating how much has the system holds
 
Thanks again mate, will give the above ago, and see what happens, wish me luck coz I haven't had much yet lol.
 
My aircon was still temperamental on my old A3 *after* I had Audi fit a new aircon compressor and clutch at huge expense.

I complained - they said it was all fixed and was tested ok before they gave it back to me. I complained again - they said bring it in. I took it in - they said "DON'T USE YOUR AIRCON UNTIL WE GET OUR AIRCON MACHINE FIXED!!!!" - DOH!

Their faulty machinery had way over gassed my system.

You've checked the fuses, fan control module, newish waster pump, new stat, coolant ...

have you unplugged each of the two stage fans and checked the continuity/resistance across the pins? Make sure they're not burnt out.

Is your stat in the right way round?

I assume your ribbed belt is still in there and tensioned properly? (Must be if the alternator is working.)

How about a dodgy earth connection? and have you checked all the other wiring to make sure there's nothing burnt out or chewed up by mischievous squirrels?

Liam
 
Hi Liam, yes m8 I have done all that also (live at an old farm house so lots of mischievous squirrels) and the ac mechine used is ok as far as I know as we done my mates at the same time, I haven't checked the resistance of the fans but have put 12 to them and they worked fine, out of the three pins then on these is one earth and the other two speed one and two? Or is that done by the signel that is given by the switch to the control mod?
 
Well he needs to do some electrical testing then.

He says the fans work when supplied power directly, so the issue is the controller isnt turning them on. Either because of a faulty switch, or because its broken. Hes said he tried shorting the switch pins out, which rules out the switch itself, leaving the controller.

Is the control module getting power? IE have you actually checked at the modules pins for 12v where it should be? Similarly for any earth wires.
 
Striped the old one down (FCM) and there wasn't anything visibly wrong with it to be honest.....plus striped and cleaned all the track for the fuse way, tested a few wires for power from the fuses and there getting to the FCM.....
 
I didn't have any power to the two stage switch plug when the ignishion was on, should there be or dose that just work on resistance? Thanks for your time on this lads....
 
Have you checked the fuses on top of the battery?
I don't mean just looking to see if they have blown, I mean physically take them out and checking them.

I had the same sort of thing happen to me and it turned out that one of the fuses (I think it was the first one) had melted at the pin. I've now bypassed it with an in-line fuse.
 
aragorn said:
Red wire at the thermoswitch should have 12v present.
Click to expand...
Right...nice one, I now have something I can work back from,

And A3 T, yes buddy I have really gone thru that one very thoroughly, thanks for the input tho,

Ive got back late tonight so I will have to tri all the extra ideas tomo, will let you know how I get on then.
 
aragorn said:
Similarly for any earth wires.
Click to expand...
no mate I haven't checked the earths as i did clean them up awhile ago so one may have been brittle and caused a brake so will do that also tomo mate cheers.
 
Have you checked the feed from the climate unit in the dash? Have you checked it's switching? If you power the pump does the clutch kick in? Have you checked the air con relay, is that switching? Have you checked the feed from the main cooling fan? Is the quantity of a/c gas correct?
 
Didn't have much time again tonight but managed to dig out the ac pressure switch, hows the best way to test it? Can I do it while it's on the car? Can I by pass the switch and bridge the two or 3 of the 3 pins to see if it lets it come on.
 
Yeah, cheers bill, after you and aragorn said there should be power to the switch I had something to go by so started testing and pulling things about lol, also thanks for getting the turbs and bits to me, they arrived this morning. :)
 
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