Intermittent air-con

[Tunny]

Hi all I hope someone can help.
I've owed my A3 for almost four months now and I'm slowly getting through the minor fault and mods. Well the time came last week to sort the air con.
When I test drove it the air con didn't kick in but with it being climate control plus the outside temp was lower than 18° I didn't think anything more of it until recently.
Things I've done and checked so far.
Had it vacuumed and re-gassed at F1 (I know but at £39 and no charge if unsuccessful it's a no brainer) as soon as it was done the blowers were freezing for about 10 minutes then nothing, so I took it back, the friendly F1 guy tested the pressure and it was fine so no leaks, it then went cold again. He told me to see how it goes as it may not have been used for a while. I used it over the weekend but it only worked every now and then.
-I get a click every-time I press air con.
-Both fans kick in every time.
-Compressor works and spins fine so I'm presuming the clutch is ok.
-I've disconnected the pressure sensor with the air con running and the fans and compressor cut off, plug it back in and they work fine again.
-I had to replace the coolant temp sensor over the weekend as the temp gauge was playing up while I was at it I noticed a white ended sensor, after a bit of googling found it's the A/C thermal switch, I've jumped the contacts today (paper clip and electrical tape) and left it disconnected from the sensor.
At this moment in time it does seem cooler than having no a/c on at all but not as cold as when the odd ten minutes it works.
Its a 98 8L 1.8t sport
Any input would be appreciated

 

[Chillout]

Hi all I hope someone can help.
I've owed my A3 for almost four months now and I'm slowly getting through the minor fault and mods. Well the time came last week to sort the air con.
When I test drove it the air con didn't kick in but with it being climate control plus the outside temp was lower than 18° I didn't think anything more of it until recently.
Things I've done and checked so far.
Had it vacuumed and re-gassed at F1 (I know but at £39 and no charge if unsuccessful it's a no brainer) as soon as it was done the blowers were freezing for about 10 minutes then nothing, so I took it back, the friendly F1 guy tested the pressure and it was fine so no leaks, it then went cold again. He told me to see how it goes as it may not have been used for a while. I used it over the weekend but it only worked every now and then.
-I get a click every-time I press air con.
-Both fans kick in every time.
-Compressor works and spins fine so I'm presuming the clutch is ok.
-I've disconnected the pressure sensor with the air con running and the fans and compressor cut off, plug it back in and they work fine again.
-I had to replace the coolant temp sensor over the weekend as the temp gauge was playing up while I was at it I noticed a white ended sensor, after a bit of googling found it's the A/C thermal switch, I've jumped the contacts today (paper clip and electrical tape) and left it disconnected from the sensor.
At this moment in time it does seem cooler than having no a/c on at all but not as cold as when the odd ten minutes it works.
Its a 98 8L 1.8t sport
Any input would be appreciated

Its kind of a funny one but providing it is operating normally on the controls side would say that your system is choking with moisture especially if it was to work when you first switch it on after an extended off period

 

[Tunny]

Cheers for the quick reply.
Yep all the controls work as they should, the A/C was freezing again this morning to the point that the windscreen steamed up. It is funny as I can drive it with the A/C on for ten mins with no joy, then park it up for five get back in and it will work great but only for about ten mins again though.
If it is "chocking with moisture" what would cause this, faulty valve, bad recharge maybe?
Thanks again

 

[Chillout]

Cheers for the quick reply.
Yep all the controls work as they should, the A/C was freezing again this morning to the point that the windscreen steamed up. It is funny as I can drive it with the A/C on for ten mins with no joy, then park it up for five get back in and it will work great but only for about ten mins again though.
If it is "chocking with moisture" what would cause this, faulty valve, bad recharge maybe?
Thanks again

Sounds typical of moisture in the system as it forms a blockage of ice at the expansion valve and will clear when the system is off al if melts however it could also be a faulty expansion valve ,it may also be worth trying changing the drier and giving it a really good vac to dry the system out

 

[Tunny]

Sounds typical of moisture in the system as it forms a blockage of ice at the expansion valve and will clear when the system is off al if melts however it could also be a faulty expansion valve ,it may also be worth trying changing the drier and giving it a really good vac to dry the system out

That sounds extremely plausible, I'll post back with my results when Ive replaced them.
Cheers ones again for your guidance you've been a massive help.

 

[pol]

This sounds the same as my problem so I'd be very interested to hear if you get anywhere. I'll update if I find the answer also.

 

[Tunny]

This sounds the same as my problem so I'd be very interested to hear if you get anywhere. I'll update if I find the answer also.

Cheers pol, it's unfortunately that you have the same issues with your A/C but to be honest I'm glad someone else has the same problem as I've searched high and low trying to find a solution (without spending a fortune) don't get me wrong if the weather in the Midlands was 20°+ for more than a few months I'd take my car to an air con specialist.
I'm still not convinced regarding it being a faulty expansion valve or moisture in the system.
I did a bit more testing over the weekend, as mentioned in my previous post every time I switch the A/C on (regardless if I get cold air or not) the clutch engages, the fans kick in the revs change.
I had a 120 mile round trip yesterday and A/C worked great for about 40 miles then stopped.
On the way home I kept turning it on then off etc... But nothing
Parked the car up for like 2 minutes got back in and it worked great again for the rest of the trip
Driving work this morning still working
Driving home nothing again, so I pulled over and turn the engine off then back on, I did this three times and the A/C started to work again.
Pulled up outside the garage kept on turning the A/C on and off, changing air flow from top to bottom to middle then on to recirculate and auto, at this point it was ****** freezing but eventually after about 15 mins it stopped working again.
Turn off the ignition then back on about five times and it started to work again.
The main thing I did notice is when I initially turn the A/C on I know if it's going to work or not because there's a slight noise behind the glove box, it's like a little gush of air, and sounds a bit like putting a bit of air in your tyre, plus the engine seems to feel a bit deeper, if that makes sense.
I'm thinking is it worth taking the glove box off and checking to see if the air flow flaps/arms are working correctly or is there a flap, valve or control unit under there. Should I even be getting the little gush of air?
One more thing I will add is the gush only happens once, it's only when it's not working at all, as soon as it does work I can turn it off and back on again with no gush.
I'm sorry to babble on, I just hope my findings help

 

[Orange225]

I'm also having the same problem. Sometimes it'll work for 5 minutes and sometimes it'll last an hour. Something also whistles/whines when the fans are on full

 

[pol]

It really does sound similar. I've only really noticed that mine will work for about 15 minutes from starting the car from cold. If I stop for a short while then re-start, the air is not cold.So it will work every morning but just for about 15 minutes!

I haven't tried tuning the ignition on and off to see if it works again. For me, I guess it's temperature related somehow.

I had a faulty fan which I replaced and had the system topped up at kwik fit who said its held the refrigerant fine but it just cuts out after about 15 minutes!

 

[Orange225]

When mine stops working, my windows don't de mist too. Right pain in the ****

 

[Tunny]

I'm also having the same problem. Sometimes it'll work for 5 minutes and sometimes it'll last an hour. Something also whistles/whines when the fans are on full

After two weeks of searching the web to no avail and thinking I'm the only one with the issue now there's three, I'm not sure about the whistle/whine as I don't get that, where does the sound come from?
Plus is yours the same, fans and compressor clutch working as it should regardless of cold air or not?

 

[Tunny]

It really does sound similar. I've only really noticed that mine will work for about 15 minutes from starting the car from cold. If I stop for a short while then re-start, the air is not cold.So it will work every morning but just for about 15 minutes!

I haven't tried tuning the ignition on and off to see if it works again. For me, I guess it's temperature related somehow.

I had a faulty fan which I replaced and had the system topped up at kwik fit who said its held the refrigerant fine but it just cuts out after about 15 minutes!

Is the compressor spinning in the middle(clutch engaging) and the fans working when the air con is switched on but no cold air coming through?
My initial thoughts were that mine was also temp related but If it is temp related surly the fans and compressor would stop, I'd bypassing the temp sensor off the rad, I did this last week and the air con starting working a lot more than previously, but for me it obviously didn't cure it.

 

[Orange225]

Dunno about all the parts working, I think the clutch is engaging as the revs drop, the sound comes from the windscreen fan area, just changed the cabin filter so that could be the culprit. I get cold air until the econ light comes on then it kicks out warm air

 

[Tunny]

Dunno about all the parts working, I think the clutch is engaging as the revs drop, the sound comes from the windscreen fan area, just changed the cabin filter so that could be the culprit. I get cold air until the econ light comes on then it kicks out warm air

I'm presuming you've got a 8P with you having econ. I'm not no expert but try these links they have/had similar symptoms, as for your whistle/while from the windscreen vent, personally it sounds as though the flap isn't opening fully and the whistle/whine is air passing through a small gap in the flap

http://www.audi-sport.net/vb/air-conditioning/67355-econ-light-permanently-why.html

ECON Light Stays On, Blows Hot Air - AudiForums.com

 

[Orange225]

Thanks tunny, I'll have a look at that. Does sound like something isn't opening properly.

 

[Tunny]

Thanks tunny, I'll have a look at that. Does sound like something isn't opening properly.

No problem mate glad to be of some help, hope you get to the bottom of your problem soon

 

[Tunny]

Air con fixed!!!!!
After dismissing replacing any parts I sprayed a shed loads of wd40 in the grove where the clutch engages on the compressor plus re-greased aux belt tensioner, being carful not to get any on the belt.
It's been working perfect since Tuesday with no issues at all. WINNER

 

[Orange225]

Nice one. I'll try that on mine. Noticed mine works for longer when I'm actually moving

 

[Tunny]

Nice one. I'll try that on mine. Noticed mine works for longer when I'm actually moving

It's defo worth a go I narrowed it down to the compressor seeming to struggle a bit and thinking the magnet on the clutch maybe caked etc....