Air Conditioning/fan problems AUDI A3 1.8SE 20V (2000 model)

[madgoose]

Hi to everybody. I have found my way to this forum (and others) because of problems that I am experiencing with my Audi a3 1.8 20v SE (non turbo)(2000 model). Recently my fan belt snapped and I needed to call the AA to recover me (annoyingly the car was booked into my local mechanics for a full service, a new timing belt, new CV joints, 4 new tyres, tracking, front brake discs and pads exactly a week later!) The reason the fan belt snapped was because the clutch/pulley system had fallen off of the air refridgeration compressor and it then eventually seized, snapping the fan belt. I was 30 miles from home with no power steering and no charge going to my battery - I made it half way before the battery gave out, then I called a "very nice man" who put a fully charged battery on my car and followed me home (thanxs again AA man). My mechanic looked at the car the following day and informed me that I could by-pass the aircon by fiting a non-air con fan belt or alternatively I would have to fit a new air refridgeration compressor and fan belt kit. I bit the bullit and purchased a new air con compressor and it was fitted at the same time the rest of the work was done. I was expecting to collect the car that evening but at 4:30 the mechanic called me and said he would not be happy releasing the car as both of the fans were constantly on and ran until the battery went flat. He suggested a new fan relay but could not get the part until he following day. When he fitted the new relay the fans ran constantly (even when cold and on start up) after the ignition was switched off both of the fans ran (at the slow speed setting) for about another 5-10 minutes before cutting out. The air conditioning is not cutting in however when a live feed is connected directly to the air refridgeration compressor the cabin does get cold (so the part does work). The air-con system is fully gassed. The mechanic has stated that the fault is not to do with the thermostat or engine cooling system but to with the air-con system gases being to hot and requiring cooling.

Any suggestions will be greatly appreciated and considered. Please feel free to ask more questions I will be as specific as I can be.

Thanxs madgoose.

One more thing. On occassions (on and off for the last 3 years) normally on a cold start (but not always) I hear 4 "peeps" coming from the rear wing on the passengers side (right hand drive car). This is where the factory fitted sub-woofer is fitted and behind that what appears to be a earthiing cable/point. I have asked Audi about this on numerous occasions but they do not know! Anybody?

[smokey0123]

The beeping is to do with the alarm backup battery being flat (will need replacing to cure).

With the fans the best place to start is to read the fault codes on the engine management, instument cluser and auto HVAC modules. I presonally think it is a problem with the coolant temperature sensor.

[Crasher]

Possibly coolant temp sender but that won’t make the fans run with the ignition switched off so the rad fan switch is a good possibility, ask him to disconnect it to see if the fans stop. The fans will not run for the A/C if the engine is switched off. He replaced the fan control unit then?

[staz1000]

Bit of a complex fault this as there are so many symptoms. Not least the fact the compressor caused the fan belt to snap in the first place.

When the fans run constantly, ignition on or off, this is normally to do with the temp sender reading that the system is still 'hot'. For example if you have been driving about all day with the air con on, especially on a hot day, when you stop, some of the refrigerant is still in gas form and the system will keep the condesor fan running to cool the gas into a liquid.

On an 8P A3 there are 2 fans at the front attached to the radiator/condensor. One just is for engine cooling and the other does both engine and air con. If only one fan is running after the ignition is switched off thsi would be for the air con, if both are running it's for the engine of course.

If the air con fan just runs non stop from switch on and then continuously after switch off I would say the air con temp sender is knackered. Because yours does actually switch off after a time this may not be the case. Although there could be a battery low cut out or just a time out circuit getting involved. I just don't know!

I would suggest disconnecting the aircon temp sender to see if it kills the fan. Or the circuit could work the other way round and you/he may need to short the sender pins to simulate the temp being within limits.

The first thing to do is comfirm whether it's the air con circuit or the engine cooling. Both systems should work the same as what I explained above.

Did the compressor actually seize or did it just fall apart? If it seized you need to be 100% sure that the pressure on the system is ok, before and during the air con being run up. It could be something causing the pressure to build up and then the compressor fails. BUT the high pressure cut out should stop the compressor before getting that high, that's just another thing I would want to be sure of before drive away with confidence. There are ways to simulate a pressure build up to check the pressure cut outs work.

To be honest if your mechanic is struggling I would go elsewhere. Audi would be my first port of call. Modern cars have lots of little extra bits in the circuits which makes it a lot harder for the lay mechanic to diagnose problems.

If that's not a route you want to follow then I would call out a dedicated ECS specialist. They should be able to suss it out no problems.

[madgoose]

^^^Thanxs for taking the time to respond fellas it is appreciated.

Mechanic worked his way through the faults and reset everything. I have now suggested the coolant sensor.

The fan relay (is the name he used for the part presuming this is what you are referring to as the fan control unit) was replaced with a new unit.

Let me explain about the compressor snapping the fan belt. About 8 months back (at night) I was driving along the dual carriage way doing about 65mph when I heard noise that sounded like something metal hitting the underneath of the engine bay. I immediatley stopped and checked with my torch but could see nothing wrong or out of place. I now believe this to be the part of the clutch pulley system coming off of the car hitting the tarmac and bouncing back up and hitting the sump (pure speculation). As summer started (yeah it did, honest), I tried to use the AC but it did not get cold, thinking that the unit needed regassing (I had a second hand compresor fitted about 3 years ago when my original failed, this unit was purchased from a breaker over the net but fitted by my local (London) AUDI dealership as a "private job on Saturday morning") I received the quarterly AUDI magazine and Eastbourne AUDI (I had moved so this was now my local Audi) were offering an "air con service" for £50 instaed of £99, I booked my car in thinking I would have the work done by the experts - after all "nobody knows Audis like Audi". I left the workshop and could feel no noticeable difference in the temperature of the AC. Had to pop into my local garage and mentioned that I had had the AC re-gassed but it was no better. It took my mechanic all of 90 seconds to see that part of the clutch/pulley system was missing. I returned to Audi and the "Technician" was not able to confirm that there should be a pulley system on the outside of the air con comp "it might be inside". I was fuming (pun intended) at this point they had obviously just connected the car to their AC re-gas machine and re-gassed it and did no more than that - obviously not even a final cabin test. They offerered to supply and fit a new ac comp for just under a £1000. The part being £750 approx and £200 approx labour. I manage to get the part new for £276 incl cariage and VAT. They did not warn me that the bearings may sieze (which is what eventually happen causing the fan belt to snap) or that I could fit a non air confan belt a temporary measure.

Sorry about the rant fellas.

Bit of a complex fault this as there are so many symptoms.

I am thinking that there could be a series of faults with the system.

On an 8P A3 there are 2 fans at the front attached to the radiator/condensor. One just is for engine cooling and the other does both engine and air con. If only one fan is running after the ignition is switched off thsi would be for the air con, if both are running it's for the engine of course.

Both a running, so based on what you have said it leans toward engine.

Did the compressor actually seize or did it just fall apart? If it seized you need to be 100% sure that the pressure on the system is ok, before and during the air con being run up. It could be something causing the pressure to build up and then the compressor fails. BUT the high pressure cut out should stop the compressor before getting that high, that's just another thing I would want to be sure of before drive away with confidence. There are ways to simulate a pressure build up to check the pressure cut outs work.

First a part fell off then the bearings seized on the remaining part. What you have described above is consistant with what I have read here...

http://www.bba-reman.com/content.asp...rs_evaporators

I am going to print out these replies and show them to the mechanic but I think it may well be time to contact a specialist.

Thanxs again fellas and if anybody else has a suggestion it will be welcome.

madgoose

UPDATE!

Just had a new G28 coolant sensor fitted today and nothing has changed. As a result of this the mechanic has disconnected both fans to prevent the battery going flat. This should be OK because I am only doing very local journeys at present and has shown me how to reconnect the fans if needed. The car is now booked into an auto-electronic expert for Monday morning to check the air-con circiuts. An air con (suspected) expert did mention to me today that the problem could lie with the air-con control unit (the part in the dash) and he wanted to remove it and send it away for inspection, later found out from my mechanic that this bloke would have called the same man that my mechanic had already put put me in contact with.

[madgoose]

mods please delete this (post not thread) as i cannot

[staz1000]

I'm in an internet cafe and I just wrote a huge reply then accidently pressed a button under the desk with my leg that switches off the computer! What a stupid place to put it!

Ok....

I just want to make sure you're clear that when I said 1 fan running is the air con I meant on the 8P A3. I don't know if the 8L is the same.

One way I recommend testing is to start up the engine from cold in ECON mode. This disables the air con and stops the condensor fan and compressor running. There should be something similar on the 8L.

Then turn off the ECON and the condensor fan will run up. As you turn ECON off and on the fan should start and stop, although it may take a few seconds for the fan to stop.

This will help to make sure you know which fan does what.

This may not help you as your fans are both running constantly but I just want to share that knowledge for future reference.

In my job and in my department in particular we have a saying 'repair by repair' i.e not 'repair by replace'. This encourages people to diagnose a fault by spending longer at it, learning the circuit and finding the actual problem at component level, often resulting in you either being able to fix the fault straight away or knowing 100% what part to demand.

I had a recent example of this on a mate's car (easier to explain than on a tank!) his cooling fans weren't working. A guy previously assumed it was the temp sender so fitted a new one, which didn't work. He the proceeded to wire in a switch to directly power the fans from the battery! I had a go and I bypassed the sensor to make sure it wasn't actually that and then found that the fans relay was broken! 2 quid to fix. Well free actually as I had one in my tool bag.

What I'm getting at is he shouldn't have just changed the coolant sensor. It's quite simple to just put a bit of wire in the end of the cable to see if you can isolate the fault. Unfortunately not everyone is skilled at electrics so you need to shop around when it comes to mechanics. Most of them are very bad at electrics and will actually admit they don't like it. Stay away from them.

If a mechanic says he's going to replace something simple like a sensor or sender (simple circuit I mean) ask him how he got to that conclusion before he does the work.

Modern cars are not sooooo easy to fault find on so it's still better to go to the 'experts'. Also if they do misdiagnose something you're more likely to get a discount on further work as it's not them that pays the bill.

We had a tank in recantly that a different depatment had been working on. The drivers control box had a fire internally so they ordered a new one. It took 2 months to arrive (Iraq and Afghan get priority) and when they fitted it it also burned out! So what did they do? Yes, they ordered another new one!!!! I got involved and it turned out a cable had been crushed when they had put the engine back in on another job and caused a short. We fixed that and then they still wanted to order the new box. I opened the box it there were 2 wires burned to a crisp, I replaced them and all was good.

Those guys were trained to fix that vehicle, I am not. But I have that ethos to investigate the fault to the deepest level I can before ordering the part. You need to find a mechanic like that.

Just make sure you first question is 'Are you any good at electrics?'. If you're not happy with his answer go elsewhere.

[madgoose]

Thanxs for taking the time STAZ1000. I think from what you have said the 8L and 8P are pretty similar in that respect. My 8L has a larger fan to the right as you face the vehicle and a slightly smaller one a bit lower and to the left. I will go through what you have suggested in the mornig (first of all connecting the fans). This does sound like a similar test that the mechanics did - having me sat in the car calling out "on", "off", "econ on", "econ on" i guess they were trying to identitify what was what and what did what.

I undertsand your statement of "repair by repair" rather than "repair by replace". In my opinion this gives you a much more in depth understanding of how something works. In this day and age it seems harder to find "engineering" mechanics, they have all become "fitter" mechanics - in other words they can diagnose a fault in the system but instead of repairing the damaged components they simply replace. This I feel is due to them being trained in ********hips were their aim is to move their stock rather than repair components, this way they get the mark up on the product and the "technicians " time. However in some situations it is economically suited to the customer to replace a suspected damaged part rather than the mechnics time being charged to the customer to fault find and repair. This I think is true in my case regarding the sensor. I also know this is the case in other industries for example IT. It comes down to knowledge and economics. I personaly would rather be riding in a tank with you and your soldering iron than have a juggernaut following along behind with enough components to build three more tanks!

I have now made an appointment for my car to go to an auto electrician who is supposed to be the best about (recommended by my mechanics- one of whom does not like the guy but did not dispute that he is good at what he does). I do not want to go back to my local AUDI *********** CAFFYNS of EASTBOURNE because i have had two bad experiences with them and they seem to slip out of the situation like eels. (Quits before going into rant mode - but that was AUDI EASTBOURNE in case anybody did not hear me). If I had not had this recommendation I was going to book the car back into the dealership I used to use in London S.G. Smith DULWICH AUDI - wonderful people!

Once again thanxs Staz1000 - I guess you disconnected and resituated the button under the desk before you left?

[Crasher]

The 8L and 8P fans have nothing in common to each other part from that they both move air and run on electricity. The 8P uses the 1K0 type pan pack which has the controller built into the larger fan, rather than being a separate unit.

[madgoose]

The 8L and 8P fans have nothing in common to each other part from that they both move air and run on electricity. The 8P uses the 1K0 type pan pack which has the controller built into the larger fan, rather than being a separate unit.

Noted - thanxs crasher.