[tilt]

Thank you all very much for responding and offering your inputs - much appreciated. I have an appointment on Monday morning (Sep 25) to have the system checked. I shall keep you posted.

Originally Posted by androdev

If you hear the blower fan sound (the sound should get louder as you dial up the blower speed) then it must be the flaps that are messed up. Try in heater mode to see if you get air flow. In the heater mode, the air comes out of the bottom vents unless you fiddle with air con dials to switch to top vents, etc.

Edit: it is easy to remove the air-con cabin filters and be able to inspect both the blower and evaporator coil.

Thank you androdev. I shall have the flaps checked too in addition to the blower and coil. However, I have a question for you: if it's the flaps that are messed up, shouldn't I be having the problem all the while instead of just in the mornings alone? The AC works absolutely fine after morning, irrespective of how short or long the drive is.

Originally Posted by Jaggu

Classic case of icing up is my suspect. AC cooling is more than what the blower can disperse off the grill, leading to icing up of AC gas. When you stop for a while, it de-freezes and starts circulating again. You can check this by just switching off the compressor switch off (leave it off for about 5 mts) while keeping fan on and then switching On just the compressor switch.

If it works then next thing to check is how the dust filters are? are they clean and and not obstructing any airflow, if so replace the filter and see how it behaves. If not you need to get a clean up of the AC cooling coil (inside the dash) along with the blower assembly.

Icing up seems to fit, from a logical perspective - since the problem happens only in the early mornings. Thank you.

It did not occur to me to test it by switching off the compressor like you suggested; and I shall not be able to do it now since I am not going anywhere that far before my appointment on Monday; but I shall ensure that VW does a thorough check of the entire system on Monday. Thank you once again.

Originally Posted by SS-Traveller

**NIP*

Two queries:
- Is the weather in your area very humid?
- Are you allowing the automatic system to choose fresh air / recirculation mode on its own, or are you forcing it manually to stay in one of the modes?

I am in Bangalore. Not very humid; and my drives are usually from Bangalore. So, maybe humidity can be ruled out?

Re. auto recirc. mode etc., my model comes with automatic recirc. mode that also apparently has a smell-filter that closes the vents when encountering outside stink! And I pretty much leave everything to run automatically, no fiddling around with anything other than the temperature setting dial.


Once again, thank you all for your inputs.

I had another related question. Someone else to whom I had put forth this same problem suggested that there was a resistor pack in the housing where the cabin air filter is; and that this resistor is the one causing the problem; and that replacing that resistor was a very easy and inexpensive fix. Would you concur?

Incidentally, the thread title is not what I originally typed - it has been changed by the mods. The current title gives an erroneous impression that the AC shuts off every time after an hour. This is NOT the case. It only shuts off after an hour in the early mornings. If I start driving a little later, say around 9 a.m., the AC never misbehaves.

Cheers

[esteem_lover]

Thermostat has failed. Get a new one.

[bhaskar.guru]

Hello all,

I'm Bhaskar currently staying in Bangalore. I have a Tata Nano Twist(Sep-2014) having done 34k on the odo. I've done stretches like Hyd-Godavarikhani, Hyd-Blr(4-5 times), Blr-Coorg road trip.

Of late I've been facing a peculiar issue where the flow of air from the AC blower reduces drastically after driving for about 45 minutes and the blower noise also increases. This happens especially on the highways.

I got it checked at the Tata service centre along with a few other snags last week. Even after that I felt the same issue and when I went again we tried recreating the issue by keeping the engine and AC On.

However we were unable to do it. Not sure whether it was because the vehicle wasn't moving or something.
He has asked me to come back so we can go for a test drive to check the same.

Has any one else faced this issue?

Any inputs would be appreciated.

[greenhorn]

does the airflow stop, or does the air still keep coming with hot air instead of cold?

http://www.team-bhp.com/forum/techni...operation.html

Might be worthwhile to consult an AC specialist

[bhaskar.guru]

Cooling is not an issue.

The airflow reduces by half this forcing me to open the windows.

[Leoshashi]

Check for clogged evaporator and proper functioning of AC cutoff. I faced the same issue in my M800 few years back, and it was due to frosting of evaporator due to AC cut off not functioning.

AC cutoff can be easily checked by parking your car under a shade or cool place, and then switching on the AC. The compressor should auto cut after some time.

Regards,
Shashi

[mercedised]

This happened with my Nano too. Later, the AC thermostat was found tobe faulty, it was not cutting-off the AC due to which ICE was being formed at the coil. Changed it and the problem got sorted out.

[Rahul Bhalgat]

I agree with Leoshashi and mercidised. If the airflow is reducing after some time, then the evaporator must be clogging, mostly due to ice formation.

To confirm this, please switch to hot air once the airflow reduces. Or just run the blower, without AC. This shall free-up the ice formed in the evaporator and the airflow shall be gradually restored.

Or you can run the AC intermittently, 5 min ON followed by 5 min OFF. This will not allow ice build-up and airflow will not reduce.

This is just to confirm the diagnosis.

[glenmz]

I have faced this couple of times in my Wagon R and once in my Fiesta and that's mostly during long drives.
The first time it happened, I was wondering what to do. The work around that I use is to turn the temperature to the hottest / warmest and the icing problem would go away and the air circulation would be back to normal.

[tilt]

I know I said I would have an update yesterday after the appointment; but it so happened that they could not accommodate me yesterday. I have been given an appointment now for Oct 3. I shall keep you posted then of what transpires.

Cheers

[tilt]

Well, the Oct 3 appointment did not show anything wrong, the VAS system showed everything to be fine; so I suggested and practically bullied the GM service to send two guys with me on an very very early morning test drive for about 300 kms. That drive happened this morning.

They came armed with their PC with VAS and the OBD cable. We drove for about 150+ kms starting at 6 a.m. from the service centre. The problem, thankfully, did manifest itself. I heaved a sigh of relief that they could now realise I was not an automotive hypochondriac or hallucinating; and that the issue really did exist.

The guys were poring over the VAS all through the drive; and could find absolutely nothing wrong. Compressor fine, blower motor fine, all voltages coming through as designed, etc; but no airflow. They tried both manual and auto; both displayed the same symptoms.

Stopped after 150+ kms for breakfast, started on the return journey around 9 a.m. And, like I mentioned in my original post, no issues at all - airflow was perfect at any speed, both auto and manual; and VAS of course said everything was working just fine as usual.

So, the mystery deepens.

They said they would once again talk to VW and send them one more scan from VAS, even though they had already said based on the previous scan that nothing was wrong with my car.

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. Here is the case: http://www.cgl.uwaterloo.ca/smann/IceCream/humor.html

Cheers

[dhanushs]

They are relying too much on electronics. Check the thermostat. Also, the gas. Did they check this?

[Chethan B G]

Originally Posted by tilt

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. Here is the case: http://www.cgl.uwaterloo.ca/smann/IceCream/humor.html

Cheers

I was thinking of the same!

Mohan, with my limited knowledge, knowing that I risk being ridiculed for my analogy, my 2 cents:

The AC compressor on a VW Jetta runs continuously (similar to an Inverter technology). There is a Solenoid controlling the flow of the refrigerant. If the valve is not operating properly, excess refrigerant may flow at times, which may lead to condensation. Once this happens, to control the cabin temperature, AC-Controller may start doing weird things. Since all components are working when tested separately, VAS will not throw any error. I don't think there is any problem with the resistors itself, except that it has a overheating fuse protection!

I am sure that you would have checked the condensation water drainage hose, on heater and air conditioner unit.

With so much of electronics combined with mechanicals in the modern day engines, trouble-shooting is not straight forward and requires a lot of logic combined with common-sense. Out of the box issues are always a challenge to solve.

All the best! Kindly update.

[Rahul Bhalgat]

Originally Posted by tilt

They came armed with their PC with VAS and the OBD cable. We drove for about 150+ kms starting at 6 a.m. from the service centre. The problem, thankfully, did manifest itself. I heaved a sigh of relief that they could now realise I was not an automotive hypochondriac or hallucinating; and that the issue really did exist.

The guys were poring over the VAS all through the drive; and could find absolutely nothing wrong. Compressor fine, blower motor fine, all voltages coming through as designed, etc; but no airflow. They tried both manual and auto; both displayed the same symptoms.

Cheers

Hi tilt,
Did you not tell them to check the possibility of evaporator clogging due to ice formation? I think it will not reflect in the OBD.

Also try the following, which I suggested earlier:
"To confirm this, please switch to hot air once the airflow reduces. Or just run the blower, without AC. This shall free-up the ice formed in the evaporator and the airflow shall be gradually restored.

Or you can run the AC intermittently, 5 min ON followed by 5 min OFF. This will not allow ice build-up and airflow will not reduce."

And I am really glad to see your love for your car that made you pursue service technicians to accompany you at 6 am for a 300 km drive.

[tilt]

Thank you all for responding.

Originally Posted by dhanushs

They are relying too much on electronics. Check the thermostat. Also, the gas. Did they check this?

Not yet. I suggested the remedies mentioned in this thread to them, they said they would wait and take the suggestions offered by VW Corporate!

Originally Posted by Chethan B G

I was thinking of the same!

Mohan, with my limited knowledge, knowing that I risk being ridiculed for my analogy, my 2 cents:

The AC compressor on a VW Jetta runs continuously (similar to an Inverter technology). There is a Solenoid controlling the flow of the refrigerant. If the valve is not operating properly, excess refrigerant may flow at times, which may lead to condensation. Once this happens, to control the cabin temperature, AC-Controller may start doing weird things. Since all components are working when tested separately, VAS will not throw any error. I don't think there is any problem with the resistors itself, except that it has a overheating fuse protection!

I am sure that you would have checked the condensation water drainage hose, on heater and air conditioner unit.

With so much of electronics combined with mechanicals in the modern day engines, trouble-shooting is not straight forward and requires a lot of logic combined with common-sense. Out of the box issues are always a challenge to solve.

All the best! Kindly update.

Bolded by me for relevance. I personally have not checked any of these, Chetan. I did mention to them that there might be freezing inside the pipes; they were completely non-committal about it.

Originally Posted by Rahul Bhalgat

Hi tilt,
Did you not tell them to check the possibility of evaporator clogging due to ice formation? I think it will not reflect in the OBD.

Also try the following, which I suggested earlier:
"To confirm this, please switch to hot air once the airflow reduces. Or just run the blower, without AC. This shall free-up the ice formed in the evaporator and the airflow shall be gradually restored.

Or you can run the AC intermittently, 5 min ON followed by 5 min OFF. This will not allow ice build-up and airflow will not reduce."

And I am really glad to see your love for your car that made you pursue service technicians to accompany you at 6 am for a 300 km drive.

Bolded by me for relevance. Yes Rahul, I did try this; and it did not make any difference. And the service guys said that this would not have helped anyway since apparently the hot-air pipes are separate from the cold-air ones. That sounded like a lot of BS to me, but hey, I do not have the knowledge or credibility to debate them.

They have opened a job card and have told me that they will call me about leaving my car there for the investigation. At that time I shall once again give them the list of recommendations made here in this thread. In fact I shall add these to the job-card as the things I want them to check and report to me on.

Once again, thank you all for responding

Cheers