[90Horses]

Originally Posted by VCheng

The proportioning valves sits in the piping to the heater core and controls the flow of hot water into the climate control unit according to the controller's commands.

Vcheng the proportioning valve was part of hvac unit, it was replaced under warranty, but the issue still exists.

Today, I have got a call from Vecto Fiat, they felt issue was subsided/solved after replacing compressor with other car. With anxious emotions i reached Vecto.

I have tested the car, issue has been reproduced, i compared vent temperatures with another Punto, results were bad.

My car:
Outside temperature: 33 C

Car hvac temperature: 21 C
Left vent temperature: 14.8 C
Right vent temperature: 7.8 C
Temperature difference ~7 C

Car hvac temperature: 23 C
Left vent temperature: 19.4 C
Right vent temperature: 16 C
Temperature difference ~4 C

Another Punto with 54K kms on ODO:
Outside temperature: 33 C
Car hvac temperature: 21 C
Left vent temperature: 6.4 C
Right vent temperature: 7.5 C
Temperature difference ~1.1 C

The above temperature difference was consistent in the other car at all temperatures. The cooling affect in this car was way better than my car. I asked the same question to the service person. He told me, even after they have changed the ac unit of the car, if you feel the issue still exists, that means there could be no problem with the car, may be this is how it was designed.

I got furious, he also told me even if FIAT looks into this issue, they would say the same. Then i asked him to show me atleast another car in Fiat plethora with same temperature readings, he said, there are 2 sensors, one is outside temperature sensor and other is engine temperature sensor, both have their effect on hvac, he will replace them and tell me if issue got solved. If not, then there is nothing they could do.

My questions:
1. I have tested vent readings of other puntos all have a temperature difference of 1-2 C in all cases. So whats wrong with expecting the same with my car. I am not ready to buy their argument that every car is different, am I doing it right?

2. After replacing everything related to AC in the car, is there any external entity of the car that could affect AC?

3. Can the above mentioned sensors could cause this issue, i dont buy it somehow ? Outside temperature sensor is located in the left orvm, and engine temperature sensor is located near ECU.

If Vecto cannot fix this, what should be my next actions.

-Sai

[ajaypjayaraj]

Looks like your left vent temperature sensor is giving false signal to the HVAC system. If everything else is working fine, this could be the problem. Did they swap the temperature sensor and check? Like VCheng mentioned yesterday, it could be tried on your car by swapping left and right temp. sensors to see if the right vent gives out warm air and left vent is getting cooled.

[90Horses]

Originally Posted by ajaypjayaraj

Looks like your left vent temperature sensor is giving false signal to the HVAC system. If everything else is working fine, this could be the problem. Did they swap the temperature sensor and check? Like VCheng mentioned yesterday, it could be tried on your car by swapping left and right temp. sensors to see if the right vent gives out warm air and left vent is getting cooled.

I do not think Punto has sensors at vent level. Only outside temperature sensor exists for Punto, please correct me if I am wrong. They are planning to change outside temperature sensor tomorrow, i will let you know the results.

[ajaypjayaraj]

Originally Posted by 90Horses

I do not think Punto has sensors at vent level. Only outside temperature sensor exists for Punto, please correct me if I am wrong. They are planning to change outside temperature sensor tomorrow, i will let you know the results.

Okay. I am not sure about it. I discovered the no. and locations of sensors in my car when trouble shooting a similar problem as yours. Even I didn't know about those sensors till then.

I assume, Punto must be having a simpler setup. Left and Right separate sensors might be there in case of dual zone and climate control. Is there climate control where you could set a temp. or is it hot/cold setting and fan speed control for AC in your Punto? Sorry, I am not familiar with Punto.

[90Horses]

Originally Posted by ajaypjayaraj

I assume, Punto must be having a simpler setup. Left and Right separate sensors might be there in case of dual zone and climate control. Is there climate control where you could set a temp. or is it hot/cold setting and fan speed control for AC in your Punto? Sorry, I am not familiar with Punto.

It is automatic climate control unit. I just set a temperature and depending on various inputs acc shall cool the car.

[VCheng]

Originally Posted by 90Horses

Vcheng the proportioning valve was part of hvac unit, it was replaced under warranty, but the issue still exists.

Today, I have got a call from Vecto Fiat, they felt issue was subsided/solved after replacing compressor with other car. With anxious emotions i reached Vecto.

..............

If Vecto cannot fix this, what should be my next actions.

-Sai

This is most curious. The only other things that come to mind are the BCM (Body Control Module) or a fault in one of the connectors, particularly ground. Also, have them check the sunlight sensor, if the car has one, in addition to the temperature sensor.

Something still doesn't seem quite right with this whole scenario. Quite perplexing indeed.

[ajaypjayaraj]

Originally Posted by 90Horses

It is automatic climate control unit. I just set a temperature and depending on various inputs acc shall cool the car.

Since most of the other hardware has been checked and confirmed to be working fine, it might be a good idea to check and confirm those various inputs (sensors) are giving the right feedback to the HVAC unit to function properly.

[90Horses]

Originally Posted by VCheng

This is most curious. The only other things that come to mind are the BCM (Body Control Module) or a fault in one of the connectors, particularly ground. Also, have them check the sunlight sensor, if the car has one, in addition to the temperature sensor.

Something still doesn't seem quite right with this whole scenario. Quite perplexing indeed.

VCheng, if the car is not grounded properly, will i get static shock after i get down the car and touch it? Because i used to get the static every time i getbdown the car and touch car's body.

[VCheng]

Originally Posted by 90Horses

VCheng, if the car is not grounded properly, will i get static shock after i get down the car and touch it? Because i used to get the static every time i getbdown the car and touch car's body.

That is a different issue. What I was referring to faulty ground connections for the different circuits on the car itself. Most good tires these days have enough conducting carbon black to make this a non-issue for static electricity, but if it bothers you, just hold the key in your hand and touch it to the car in the door jamb as you get out. No shocks, ever.

[Captain Slow]

Originally Posted by 90Horses

My car:
Outside temperature: 33 C

Car hvac temperature: 21 C
Left vent temperature: 14.8 C
Right vent temperature: 7.8 C
Temperature difference ~7 C

Car hvac temperature: 23 C
Left vent temperature: 19.4 C
Right vent temperature: 16 C
Temperature difference ~4 C



My questions:
1. I have tested vent readings of other puntos all have a temperature difference of 1-2 C in all cases. So whats wrong with expecting the same with my car. I am not ready to buy their argument that every car is different, am I doing it right?

2. After replacing everything related to AC in the car, is there any external entity of the car that could affect AC?

3. Can the above mentioned sensors could cause this issue, i dont buy it somehow ? Outside temperature sensor is located in the left orvm, and engine temperature sensor is located near ECU.

If Vecto cannot fix this, what should be my next actions.

-Sai

Can you repeat this test at night time? when the ambient temperature is much lower?
I would redo this when the ambient temperature is much lower.

I asked this earlier too. Was any leak test done for the AC?

[90Horses]

Originally Posted by Captain Slow

Can you repeat this test at night time? when the ambient temperature is much lower?
I would redo this when the ambient temperature is much lower.

Is this test still required? The other cars that I tested have 1C difference between central vents at all times, it is my car which has such peculiar issue.

My car's outside temperature sensor had some peculiar behavior. When I start the car in morning, it takes around 10-15 minutes time to reflect the new temperature, you see this as an issue with the sensor?

Originally Posted by Captain Slow

I asked this earlier too. Was any leak test done for the AC?

I asked this question to Vecto, they say, yes sir! but I doubt it. God knows whats happening with my car . Yesterday night I could not get sleep as all options ran out of hand, I just did not know what to check now !!

I am so thankful for your inputs bro. They will change the sensors today and let me know the results by end of the day, I keep you updated.

[71Convertible]

I'm not familiar with Fiats. In many mercedes models (w211, 204/203etc), drivers side blowing warmer is a symptom of low refrigerant pressure.

[Jeroen]

Originally Posted by 71Convertible

I'm not familiar with Fiats. In many mercedes models (w211, 204/203etc), drivers side blowing warmer is a symptom of low refrigerant pressure.

Actually, that is a possibillity. I remember something similar a couple of years ago on my Jeep Cherokee. I was getting some uneven distribution of the cold air as well. Checked the Cherokee forum and was advised the same.

If the system is not filled properly the surface temperature of the evaporator might start showing considerable differences. So a certain volume of air might be cooled more than an other part. Depends on the layout of the various air ducts what effect you would see.

Easy check, well at least in the USA. You can buy at any car part store a little bottle of refrigrant filler with a manometer. Takes two minutes!

Good luck with it .
Jeroen

[90Horses]

I was called by Vecto Fiat team yesterday, they told me, issue is not fixed even after changing everything related to AC and it is better if I talk with Divisional manager and let the FIAT come and check the vehicle. I agreed and visited Vecto Fiat.

I was shocked, I could not believe car is not fixed even after they changed everything. I opened a link in internet and asked him to replace compressor relay, started the car and got a difference straight away and it subsided by the time and issue has popped up.

Then, I remembered my wife's words that she told me the day before, "If everything related to AC is replaced and still issue exists, then problem is with something that is not replaced as part of AC and works along with AC". That words struck me like a stone.

I asked the guy, did u change Pollen Filter? He said I do not know sir, may be they would have changed! I have doubted, I asked him to run the car's AC without the Pollen Filter, some technician has come and removed the Pollen Filter, my doubts were true, they did not even touch the Pollen Filter module, it has leaves and dust etc.. Btw, it is a new pollen filter fitted 2K kms before.

Started the car and voila car's AC is back, at all times temperature difference was less than 1.5 degrees. I have tested the car for 2 hours straight, car's AC behaved as it was perfect. I was shocked, guy was shocked, I asked him, HVAC unit and other units of AC are placed, but you did not check the pollen filter?? . He was silent.

So my theory is, Vecto Fiat did not clean the Pollen Filter housing and just inserted a new Filter causing some debris to sit inside the housing and jamming the central left vent and hence causing the temperature difference. Can this really happen?? Please guys, provide me with your comments!

It was 07:30 PM, I spoke with all of the executives of FIAT including Divisional manager, they said, today they will fix a new Pollen filter, pressure clean the Pollen Filter housing and do a thorough test and let me know.

Until I test my car, Vecto Fiat does not have data about the vent temperatures after replacing parts, it was me who sat with the guy and verified temperatures and noted down as if I was fixing the car for him.

I have noted down the temperature difference after and before pollen filter removal, please have a look.

[Jeroen]

Very good you are taking all these measureements. Im not sure I understand why the compressor relais could have such an impact. Which relais is it, is it just the on/off switch or does it control something else?

Bit of an embarrassement for Fiat not to think about the pollen filter.

Jeroen