Help Fire(s)!

Andrew

A2OC Donor
England
Good Afternoon,

I need some help, maybe not as dramatic as the title suggests but still very concerning.

The A2 is a 55 plate FSI (but not an FSI problem) but I don't think that matters but I include it for completeness as I encourage other posters to do always.

To start at the beginning. I have three quite good spare Climate Units that I thought I would sell in the Marketplace.

Climate 2

The button housing needed some work and not wanting to sell faulty goods I thought it only right to rectify. Removed button housing and completed a strong repair after a couple of attempts with different approaches and rebuilt. Thinking I needed pictures for a selling advert popped out my current Climate from the dash and set about connecting this one, secured all connectors and just about ready to push fully home when I noticed smoke pouring out of its vents. I mean lots of smoke, I was concerned for my safety and opened the door for a quick exit, remember thinking if this goes 'puff' into flames I am in real trouble. However, no flames and set about panic release of all connectors, pulled from dash and it took several minutes for the smoke to stop.

1683730038718.jpeg


1683730111241.jpeg


1683730174424.jpeg


1683730252847.jpeg


It transpires the smoke was the PCB locating peg on the left melting. I have met this kind of thing before, it is unbelievable how much smoke a small piece of plastic can generate.

A couple of pertinent points. I am not sure if the ignition was on and the battery not disconnected. The button housing is from a 8L unit but I can't see how that matters.

Currently I am baffled by what caused this. The work on the button housing is completely external to any electrics, the box will only go back together in one way and the connectors impossible to misconnect by their design.

Climate 3
With hindsight I rather foolishly put the Climate 2 unexplained event as 'one of those things' and moved on to Climate 3. With this I noticed the button housing was a little loose and not connecting firmly with the back box and not wanting to sell faulty goods I thought it only proper I should repair. Stripped it down and soon spotted the problem was the securing posts had split and the fixing screws would not tighten. First repair failed but a second strategy worked well and I rebuilt the climate and as before I needed pictures for an advert. Set about installing in the dash, connected the two wire connector on the right which I suspect is the main source of power and I had just connected the next multipin black connector and you've guessed it, I saw smoke appear. Pulled out connectors fast and this time not as much damage.

1683734631039.jpeg


1683734701478.jpeg

1683734750504.jpeg


I am fairly sure the ignition key was in but off and the battery not disconnected. This time the button housing is original to the back box.

There is something wrong but what I am clutching at straws, any advice welcome but as it stands I have no climate, no way I am going go put my mint climate with heated rollers back in until this is sorted. In the short term not a problem but obviously has to be fixed. The car drives fine by the way.

If you are thinking what happened to Climate 1, I embarrassingly managed to get superglue over the face, grrr, at least I can retrieve with a strip down and repaint but still two or three hours work.

Not a good week.

Andy
 
Good Afternoon,

I need some help, maybe not as dramatic as the title suggests but still very concerning.

The A2 is a 55 plate FSI (but not an FSI problem) but I don't think that matters but I include it for completeness as I encourage other posters to do always.

To start at the beginning. I have three quite good spare Climate Units that I thought I would sell in the Marketplace.

Climate 2

The button housing needed some work and not wanting to sell faulty goods I thought it only right to rectify. Removed button housing and completed a strong repair after a couple of attempts with different approaches and rebuilt. Thinking I needed pictures for a selling advert popped out my current Climate from the dash and set about connecting this one, secured all connectors and just about ready to push fully home when I noticed smoke pouring out of its vents. I mean lots of smoke, I was concerned for my safety and opened the door for a quick exit, remember thinking if this goes 'puff' into flames I am in real trouble. However, no flames and set about panic release of all connectors, pulled from dash and it took several minutes for the smoke to stop.

View attachment 107891

View attachment 107893

View attachment 107894

View attachment 107895

It transpires the smoke was the PCB locating peg on the left melting. I have met this kind of thing before, it is unbelievable how much smoke a small piece of plastic can generate.

A couple of pertinent points. I am not sure if the ignition was on and the battery not disconnected. The button housing is from a 8L unit but I can't see how that matters.

Currently I am baffled by what caused this. The work on the button housing is completely external to any electrics, the box will only go back together in one way and the connectors impossible to misconnect by their design.

Climate 3
With hindsight I rather foolishly put the Climate 2 unexplained event as 'one of those things' and moved on to Climate 3. With this I noticed the button housing was a little loose and not connecting firmly with the back box and not wanting to sell faulty goods I thought it only proper I should repair. Stripped it down and soon spotted the problem was the securing posts had split and the fixing screws would not tighten. First repair failed but a second strategy worked well and I rebuilt the climate and as before I needed pictures for an advert. Set about installing in the dash, connected the two wire connector on the right which I suspect is the main source of power and I had just connected the next multipin black connector and you've guessed it, I saw smoke appear. Pulled out connectors fast and this time not as much damage.

View attachment 107899

View attachment 107900
View attachment 107901

I am fairly sure the ignition key was in but off and the battery not disconnected. This time the button housing is original to the back box.

There is something wrong but what I am clutching at straws, any advice welcome but as it stands I have no climate, no way I am going go put my mint climate with heated rollers back in until this is sorted. In the short term not a problem but obviously has to be fixed. The car drives fine by the way.

If you are thinking what happened to Climate 1, I embarrassingly managed to get superglue over the face, grrr, at least I can retrieve with a strip down and repaint but still two or three hours work.

Not a good week.

Andy
Could you take a pictures of the reverse side of both PCBs please? Ideally, a pic of the whole PCB, then a close up of the damaged area.
Mac.
 
Could you take a pictures of the reverse side of both PCBs please? Ideally, a pic of the whole PCB, then a close up of the damaged area.
Mac.
As requested, this is the least damaged one on the grounds it might show the source of the problem better.

1683739850511.jpeg


1683739923928.jpeg


Andy
 
Not saying that this is relevant but out of interest does BOTH the radiator fan and blower fans rotate as and when expected. Also does the cabin temperature sensing fan inlet contain and debris?
 
Not saying that this is relevant but out of interest does BOTH the radiator fan and blower fans rotate as and when expected. Also does the cabin temperature sensing fan inlet contain and debris?
Its started to rain now so observation of radiator fan under the bonnet (?) will have to wait until tomorrow. By blower fan I take it you mean the cabin blower under the glovebox, but will that work without a climate? The little vents and its fan blades were clean - I probably cleaned them.

Thanks.

Andy
 
Could you take a pictures of the reverse side of both PCBs please? Ideally, a pic of the whole PCB, then a close up of the damaged area.
Mac.
My best thought is that somehow, the ground. (0v), track, that is the heavy metal "track" in the back of the panel is shorting to the track adjacent to the hole in the PCB, where the PCB support goes through. I'm guessing, (not having seen one in the flesh), that a small screw threads into the support pillar. The screw gets hot, so plastic melts/and fumes. If so, that screw has, somehow, become electrically connected to the ground track.
If my guess at the construction is wrong, then just ignore the above.
Mac.
 
Need a base line to start from.

Prior to fitting these 2 climate units everything was OK? Have you connected anything into the power line for the climate? Are the correct rated fuses in the fuse box?

All 2 climate units have been worked on - True? All 2 suffered the same failure with components in the same area being destroyed? Climate signals the radiator cooling fan to rotate at slow speed for condenser air flow and also tells the cabin blower / blower fan to activate at various speeds

Perhaps the fascia securing screws have somehow become mixed up and a longer screw could now be causing the short. Remember they are earthed on the chassis. The circuit board is either physically shorting out, or the ribbon cable is incorrectly connected and end up providing power where it should not be. Thoroughly check the wiring looms for melted wires or damaged wires. Remember many items on the a2 are negative switched unlike the more traditional positive switched.
 
My best thought is that somehow, the ground. (0v), track, that is the heavy metal "track" in the back of the panel is shorting to the track adjacent to the hole in the PCB, where the PCB support goes through. I'm guessing, (not having seen one in the flesh), that a small screw threads into the support pillar. The screw gets hot, so plastic melts/and fumes. If so, that screw has, somehow, become electrically connected to the ground track.
If my guess at the construction is wrong, then just ignore the above.
Mac.
Good Evening Mac,

The hole in the PCB is for something that appears to me to be no more than a locating post. Once the two posts have done their locating job the board is fixed by 5 screws round the outside to the button housing and become redundant. No screw in the post.

Thanks. - Andy
 
Evening Andy,

I’ve seen this shorting in the exact same place before…

A few years ago (2016 I think) when swapping climate panel fascias whilst still connected to the car (pretty sure the ignition off but it was some time ago now.) this happened to me. What actually happened during my inexperienced rushed process was the black plastic 4 pin cover come off:

IMG_6965.jpeg


This left the 4x 2 pronged pins inside it being exposed and one of them joined the incorrect pin on the small fan when pushing the panel back on. It instantly started smoking and burnt out in the same place. Could this if somehow happened?

If this was not the case and this 8L housing was as Audi intended then it should be a massive warning to not connect up a climate panels rear housing if it was not meant for the A2. From what I read and see above, there is evidence here that the supply fuse has not blown and had you not notice the issue as quick as you did then it could have been a lot worse.

I’m a massive fan of trying other VAG parts in our fleet but I’ll certainly not be trying an 8L climate panel housing. Thanks for sharing and hope it saves someone from doing the same in the future Sir.

Kind regards,

Tom
 
Need a base line to start from.

Prior to fitting these 2 climate units everything was OK? Have you connected anything into the power line for the climate? Are the correct rated fuses in the fuse box?

All 2 climate units have been worked on - True? All 2 suffered the same failure with components in the same area being destroyed? Climate signals the radiator cooling fan to rotate at slow speed for condenser air flow and also tells the cabin blower / blower fan to activate at various speeds

Perhaps the fascia securing screws have somehow become mixed up and a longer screw could now be causing the short. Remember they are earthed on the chassis. The circuit board is either physically shorting out, or the ribbon cable is incorrectly connected and end up providing power where it should not be. Thoroughly check the wiring looms for melted wires or damaged wires. Remember many items on the a2 are negative switched unlike the more traditional positive switched.
Good Evening Graham,

Everything worked correctly before, in fact Tom installed my climate as a heated seated upgrade but as you will know this independent of the climate. As far as I know no extras and I assume the fuses are correct.

I do not know the climates histories.

I think we can discount screws causing a problem, even if too long they go into plastic and would come through the face! You have touched on something with the ribbon cable that is my main suspect.

For anybody who is not familiar with the innards of a climate unit the ribbon cable that connects the front PCB to the board in the back box passes through a large tunnel with the ribbon cable having excess length to accommodate the button housing moving a touch away from the back box to enable assemble/disassembly of the button housing, as per pictures. The largeness of the tunnel is there to accommodate the bunched up cable when the unit is fully assembled, the cable lies in a large graceful loop.

On assembly of the button housing to the back box I have been shovelling the excess length into the tunnel with fingers but as the gap reduces to half an inch the fingers have to be withdrawn and now the rub you just hope the ribbon cable has enough stiffness to push the rest of the cable back to form its graceful loop, wire shape memory helps as well. But what if which I suspect has happened the front portion of the cable has folded back on itself to rest on the front board to cause shorting, notice the smoke stained cable. Puzzling as each wire in the ribbon cable has its own insulation layer. I hope that made sense

If I try this again I have a plan to loop a cotton thread round the cable and out of the back box through the top vents and use to ensure the ribbon cable is pulled back, retrieving the cotton thread when happy.

Thanks for your input.

Andy
 
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Evening Andy,

I’ve seen this shorting in the exact same place before…

A few years ago (2016 I think) when swapping climate panel fascias whilst still connected to the car (pretty sure the ignition off but it was some time ago now.) this happened to me. What actually happened during my inexperienced rushed process was the black plastic 4 pin cover come off:

View attachment 107912

This left the 4x 2 pronged pins inside it being exposed and one of them joined the incorrect pin on the small fan when pushing the panel back on. It instantly started smoking and burnt out in the same place. Could this if somehow happened?

If this was not the case and this 8L housing was as Audi intended then it should be a massive warning to not connect up a climate panels rear housing if it was not meant for the A2. From what I read and see above, there is evidence here that the supply fuse has not blown and had you not notice the issue as quick as you did then it could have been a lot worse.

I’m a massive fan of trying other VAG parts in our fleet but I’ll certainly not be trying an 8L climate panel housing. Thanks for sharing and hope it saves someone from doing the same in the future Sir.

Kind regards,

Tom
Good Evening Tom,

Apologies typing my last post before I looked at yours.

Thanks for this I will look at this connector closely tomorrow.

I am still happy to use an 8L button housing as I am fairly certain the second climate was all factory A2.

Andy
 
On assembly of the button housing to the back box I have been shovelling the excess length into the tunnel with fingers but as the gap reduces to half an inch the fingers have to be withdrawn and now the rub you just hope the ribbon cable has enough stiffness to push the rest of the cable back to form its graceful loop, wire shape memory helps as well. But what if which I suspect has happened the front portion of the cable has folded back on itself to rest on the front board to cause shorting, notice the smoke stained cable. Puzzling as each wire in the ribbon cable has its own insulation layer. I hope that made sense

If I try this again I have a plan to loop a cotton thread round the cable and out of the back box through the top vents and use to ensure the ribbon cable is pulled back, retrieving the cotton thread when happy.

Thanks for your input.

Andy
Forgive the (momentary) thread swerve, but for the un-initiated - can you confirm that this is only likely to happen with the unit being opened up rather than simple removal and re-installation of a Climate unit to the dashboard? I have to remove and replace ours one by one later this month for soft-touch refurbishment and this thread has given me a bit of angst that my ineptitude at this process could cause a similar issue.
 
Good Evening Graham,

Everything worked correctly before, in fact Tom installed my climate as a heated seated upgrade but as you will know this independent of the climate. As far as I know no extras and I assume the fuses are correct.

I do not know the climates histories.

I think we can discount screws causing a problem, even if too long they go into plastic and would come through the face! You have touched on something with the ribbon cable that is my main suspect.

For anybody who is not familiar with the innards of a climate unit the ribbon cable that connects the front PCB to the board in the back box passes through a large tunnel with the ribbon cable having excess length to accommodate the button housing moving a touch away from the back box to enable assemble/disassembly of the button housing, as per pictures. The largeness of the tunnel is there to accommodate the bunched up cable when the unit is fully assembled, the cable lies in a large graceful loop.

On assembly of the button housing to the back box I have been shovelling the excess length into the tunnel with fingers but as the gap reduces to half an inch the fingers have to be withdrawn and now the rub you just hope the ribbon cable has enough stiffness to push the rest of the cable back to form its graceful loop, wire shape memory helps as well. But what if which I suspect has happened the front portion of the cable has folded back on itself to rest on the front board to cause shorting, notice the smoke stained cable. Puzzling as each wire in the ribbon cable has its own insulation layer. I hope that made sense

If I try this again I have a plan to loop a cotton thread round the cable and out of the back box through the top vents and use to ensure the ribbon cable is pulled back, retrieving the cotton thread when happy.

Thanks for your input.

Andy
You're thinking a sharp, (ish), wire end of a component pierced the ribbon cable sheath. Quite possible.
Mac
 
If you have a multi-meter and basic circuit knowledge you can trace the damage back to a couple of pins at the headers and then this would give you an indication.

I could give it a go but I am not sure what the cost would be to ship it over.

EDIT: The affected area is around the LM2904 opamp, of which I can spot two on the PCB. It is an amplifier but without some probing I don't know what their function is on this circuit.
 
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Thanks for the new pics. Could you clean up the board, around the seat of the problem? I'd use a brush, with short bristly bristles, (?), and a mild solvent, white spirit lake. The plan would be to remove the soot, so that we may be able to see the track that caused the short, it should look oxidised, with most of the solder tinning gone.
This is the area I mean.
Screenshot 2023-05-11 12.00.39.png


Mac.
 
Forgive the (momentary) thread swerve, but for the un-initiated - can you confirm that this is only likely to happen with the unit being opened up rather than simple removal and re-installation of a Climate unit to the dashboard? I have to remove and replace ours one by one later this month for soft-touch refurbishment and this thread has given me a bit of angst that my ineptitude at this process could cause a similar issue.
Good Afternoon Robin,

I can confirm my woes must be connected with opening (& closing) the climate unit. Simply removing and replacing the climates should not cause any problem.

Andy
 
@PlasticMac @Evripidis

Good Afternoon Mac &, Evros,

Thanks for the interest and offers of support but having zero knowledge of PCB work I will leave for now and pursue the more likely cause suggested by Tom.

Andy
If I can help, I've more than a bit of experience of pcbs, post it down here. Mrs Mac is, (well forty years ago was), a NASA Certifier pcb assembler. Before the advent of flow soldering and surface mount etc. A dab hand with a hot iron
Not bad at soldering either. Boom boom.
Mac.
 
Evening Andy,

I’ve seen this shorting in the exact same place before…

A few years ago (2016 I think) when swapping climate panel fascias whilst still connected to the car (pretty sure the ignition off but it was some time ago now.) this happened to me. What actually happened during my inexperienced rushed process was the black plastic 4 pin cover come off:

View attachment 107912

This left the 4x 2 pronged pins inside it being exposed and one of them joined the incorrect pin on the small fan when pushing the panel back on. It instantly started smoking and burnt out in the same place. Could this if somehow happened?

If this was not the case and this 8L housing was as Audi intended then it should be a massive warning to not connect up a climate panels rear housing if it was not meant for the A2. From what I read and see above, there is evidence here that the supply fuse has not blown and had you not notice the issue as quick as you did then it could have been a lot worse.

I’m a massive fan of trying other VAG parts in our fleet but I’ll certainly not be trying an 8L climate panel housing. Thanks for sharing and hope it saves someone from doing the same in the future Sir.

Kind regards,

Tom
Good Afternoon Tom,

Your post last night deserves a fuller reply. Can I ask how you know the little connector was the source of your meltdown, no sign of arcing on prongs or connector with mine.

However I think you might have hit the nail on the head especially after something revealing yesterday. On one climate at least there was an odd thing with no connector on the prongs from the board when I stripped the carcass for the pictures. Some pictures for those who might not be familiar.

Just look like forks as in 'knives & forks' great for dinner service in a dolls house!

1683817345474.jpeg


I gave the connector a prod with a small screwdriver down its tunnel but it did not want to move, came to the conclusion it was stuck on the counter prongs from the the little fan and I left it in. The exposed prongs seemed to slide home nicely when I pushed the button housing onto the back box.

I have for years thought this connecting arrangement was a poor design, no locking mechanism just pulls off and nothing to stop two prongs going into one conductor and all depends on friction.. For those unfamiliar you are working 'in the dark' having introduced the connector into its 15mm long tunnel you cannot see anything on assembly. The final push home of the front facia comes with the HOPE all goes well with the four prongs mating satisfactorily with no shorting hazard created. Always thought this method of working was dodgy but must have been lucky up to this week and my luck ran out.

The tunnel, vertical in picture

1683819942379.jpeg


Now the really odd thing, yesterday evening when I was taking pictures the connector fell out.

I HAVE A BETTER IDEA - Remove the little fan first!

Check the connector sits on the forks correctly.

1683821329885.jpeg


Fan in situ..

1683820404506.jpeg


... and removed.



1683820502315.jpeg


The fan showing with its prongs.

1683821913601.jpeg


Replace button housing.

1683821601011.jpeg


This way nothing to impede the connector instead of push button housing home and hope.

Now replace fan, the benefit is you can see what you are doing, ensuring each prong on the fan mates into one conductor in the connector. Sorry no way to take a picture.

Back together - SORTED.

1683822683544.jpeg


I still have 4 A2 climates and 6 other model carcases (from a long time ago for facias to retrim, heated rollers, hard touch buttons). Over the weekend I will strip one down and rebuild, reinstall but this time I am confident there will be no need to call the fire brigade.

Live and learn best by your own mistakes.

Andy
 
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