[Dr.AD]

Hi Tilt,

Given that you have tried everything obvious and it did not work, I totally agree with your following observation that this needs some out of the box thinking. I know this is a painful problem for you, but this is nevertheless very interesting problem to "debug" :-)

Originally Posted by tilt

What I need now is for someone at corporate to seriously think outside the box and come up with things to look at instead of blindly replacing the compressor or the blower etc.

My case reminds of of the story of a Pontiac from General Motors misbehaving when the owner drove to the store to buy vanilla ice cream but never misbehaved when buying any other flavour.

So I maybe completely wrong here, but trying to think outside the box as you have already tried everything else.

Before that, let me say that I do not think this is the issue of condenser/evaporator freezing up. I faced that issue in my Palio a few years ago, and that used to happen whenever certain temperature and humidity conditions were met, regardless of the time of the day or the length of the drive.

Your problem is specific to the time of the day, and the length of the drive. That makes it more interesting.

I read your original post again, and the following line drew my attention.

Originally Posted by tilt

The sound is there, as though the fan is on and blowing, but there is no blow at all. All sound, no action

Now I have faced this in my car (SX4) once or twice. There was all the sound of the fan, but no airflow. Turned out I had mistakenly left the vent position to "windscreen defogger". In that case, you will hear the fan loud and clear, but unless you put your hand in front of the vents blowing on the windscreen, you will think there is no airflow at all.

So is there a small possibility, maybe a tiny one, that in your case, when that happens, the airflow is actually being directed to windscreen? And of course, VAG software will show everything to be all OK, because it is!

Does Jetta have any humidity sensor? If Jetta has any humidity sensor (I don't know if it does or does not; but I read that some German cars do), then it is possible, that after a fresh morning drive for an hour or so, the cabin builds enough humidity that the sensor detects, and changes the airflow to windscreen, preventing any potential fogging issue. Did you by any chance see any correlation of this happening with some fogging on windscreen?

Now why would this happen only in the morning? The conditions are anyway ripe for windscreen defogging to happen in the morning. Besides, surprisingly, one very unique factor appeared in my reading about humidity in the car. When the driver and/or passengers take morning shower and start driving, they significantly add to the humidity for first hour or so. After you take your breakfast break, this humidity is gone by then.

Again, this could (very likely) all be a totally wrong theory, and the problem could be something else. But since we are looking for "out of the box" solution, I thought of this possibility.

Besides, the fact that the fan makes the sound, but there is no airflow, only indicates that there must be some vent where the air is going. Because when the fan makes sound, it is rotating, and it is indeed physically pushing the air. That air has to go somewhere. Whether that air is cold enough or not is secondary question (which is relevant to condensation etc.). The primary question is where is that air escaping from, and the most obvious answer (to me) sounds like the windscreen vents.

If the fan did not make any sound and appeared dead, then the whole hypothesis above is ruled out. But you mentioned the fan makes the usual sound. And hence this theory.

I am very tempted to ask you for an early morning 300km ride to check this out :-)

Cheers!
-AD

[tilt]

Interesting train of thought Dr.AD And yes, we can certainly do another 300 km drive any time you're ready, to test your hypothesis.

I do not know if the Jetta has a humidity sensor, but since it is auto climate control where even the vents are decided automatically, I am quite liking your theory. However, one observation that goes against this line of thought is that there have been many times when my windscreen begins to fog up at the bottom and the system does nothing to clear it - I have to use my wipers then to remove the fogging. So, that's something to think about.

The shower argument (boy, talk about out of the box - this is out of Earth's atmosphere LOL), that wouldn't hold water either (see what I did there? LOL), since all our drives (you have been on almost all of them) including today's were done long after the shower, and included time spent outside the car waiting for the service centre guys to show up.

So, let me know when you want to go on a test drive!

Cheers

[Dr.AD]

Originally Posted by tilt

I do not know if the Jetta has a humidity sensor, but since it is auto climate control where even the vents are decided automatically, I am quite liking your theory.

Exactly! During our usual early morning drives, one weird problem I face in my SX4 (which also has automatic climate control including automatic vent positions) is that even if I set the temperature 1C above the ambient (say outside temperature is 21C, which is typical in early mornings, and I set inside temperature to 22C), then it blows all the air only on my feet. The reason is that the AC unit "thinks" that the inside air (22C) is hotter than outside air (21C), and the hot air needs to be blown down because then it will rise up, being lighter. All fine, but it is very annoying to have air at 22C blown on your feet with full force. I switch the AC to manual mode in such cases.

Even this problem happens only in the early morning drives, and only for first one hour or so, due do the typical temperature differences we are talking about. The problem does not repeat through the day later.

So, the automatic climate control units are known to use the vent selections in a funny way. Maybe something similar is happening in your car. And one thing in my car is that even if I switch the main AC to manual mode (from auto mode), the vent selection still remains in its own auto mode unless I switch that to manual too. So something similar in Jetta maybe? Next time you fiddle with the manual mode, please check changing the vent position manually to front vents, and you may be surprised to find that powerful gust of air that you have been missing.

However, one observation that goes against this line of thought is that there have been many times when my windscreen begins to fog up at the bottom and the system does nothing to clear it - I have to use my wipers then to remove the fogging. So, that's something to think about.

OK, this is true. So there is something else at play. Anyways, just try the manual vent selection once and we will know.

Another out of the box theory: Maybe, given the cold morning temperatures to being with, within an hour of driving, your inside temperature gets perfectly matched to the set value. And then, instead of gradually reducing the airflow, some "bug" in the system just stops the flow, or worse yet, redirects it to windscreen vent or some other vent that you don't notice ("all sound, and no action").

When you take that break, the car interiors sufficiently heat up, and later throughout the day the outside temperatures are higher so this "point of thermal equilibrium" never happens through the day again.

I know that thermodynamically speaking, what I said is not accurate, or not even correct, but I am trying to do some thinking aloud to at least find some possibilities that the VW service guys might never find, and the possibilities that relate to the morning time peculiarity :-)

The shower argument (boy, talk about out of the box - this is out of Earth's atmosphere LOL), that wouldn't hold water either (see what I did there? LOL), since all our drives (you have been on almost all of them) including today's were done long after the shower, and included time spent outside the car waiting for the service centre guys to show up.

LOL. This is getting funny. Yes, the shower argument is probably too out of the box to be true. It indeed does not hold any water (liked your choice of words). :-)

So, let me know when you want to go on a test drive!

Definitely. Will ping you soon and let's test this out.

[spirits999]

Did you find a solution to this? I faced similar issue with my 3 series GT

[tilt]

Originally Posted by spirits999

Did you find a solution to this? I faced similar issue with my 3 series GT

I apologize for letting you hang without a response - it is just now that I even saw your post.

Yes the issue is resolved - I posted the solution here: https://www.team-bhp.com/forum/techn...ml#post4338360 (Air-con Blower not working)

It was indeed the evaporator sensor that was borked. Once it was replaced I have not faced the issue since.

Cheers

[prabhu.reddy92]

Originally Posted by tilt

Car: 2015 Jetta TDI DSG Highline Facelift model with automatic climate control, run 54000+ kms, .

This is the second problem that my car has that no one seems to have heard of and no other car but mine has ever had. It happens as though it is on a pre-programmed schedule, only in the mornings.

I had somewhat similar issue in my 2011 Santro Xing. The AC blower and everything was working fine but no cooling when i drove it for more than 100kms. I experienced this earlier when i was driving in city for more than an hour continuously but i didn't take it seriously and one fine day i was on a road trip to Pondicherry from Bengaluru on a very sunny day where i experienced this issue again and passengers started complaining too that AC is not working. So I visited the Hyundai service centre in Krishnagiri and they said that the issue is with the AC coil but later it turned out that the radiator was blocked by some foreign material and due to that engine is not being cooled and the high temperatures made the ECU to cutoff compressor by reducing the load on the engine. The temperature bar on the speedometer was on higher side when this happened which i saw only when a light amount of smoke started coming from the engine after driving for about 200 kms continuously. Had tochange entire radiator and fresh coolant too.

It might be a different issue in your car but it did sound similar to me so sharing my story. Please let me know if it helps.

[tilt]

Originally Posted by prabhu.reddy92

I*SNIP*

It might be a different issue in your car but it did sound similar to me so sharing my story. Please let me know if it helps.

Thank you for sharing your experience. The issue with my car was different from yours and I have linked above to the solution. It has been resolved and has since been working perfecvtly without any problems.

Thanks once again and cheers