# In cabin A/C temperature sensor



## neu318 (Feb 18, 2003)

So I was browsing ECS tuning a few weeks ago and noticed they have for sale a Temp sensor that supposedly goes near the in cabin air filter underneath the glovebox. It says a bad sensor can cause the A/C not to perform properly. I've been having issues with my A/C for a while, takes long to cool on some days. This sensor was only $7 so I figured why not give it a try. Was wondering if anyone else has heard of it or has attempted to install it. 

Link for sensor: http://www.ecstuning.com/Audi-A3-Quattro-V6_3.2L/Search/SiteSearch/Temperature_Sensor/ES2575456/


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## JaseZilla (Feb 20, 2012)

You know, for the price it may not be a bad thing to try. Although I believe most of us supper from bad compressors that need replaced, this may remedy some peoples issues. Im sure shipping will be more than the part as ecs is notoriously famous for high shipping costs and slow send time, still may be worth a try.


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## neu318 (Feb 18, 2003)

JaseZilla said:


> You know, for the price it may not be a bad thing to try. Although I believe most of us supper from bad compressors that need replaced, this may remedy some peoples issues. Im sure shipping will be more than the part as ecs is notoriously famous for high shipping costs and slow send time, still may be worth a try.



Yeah, I'm trying to tell myself that it isn't the compressor, lol. I forgot to mention that I did order it. I had ordered some other stuff so shippping didn't hurt too much. I have it already. I'm going to try to tackle it this weekend. I'll post back results..


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## JaseZilla (Feb 20, 2012)

neu318 said:


> Yeah, I'm trying to tell myself that it isn't the compressor, lol. I forgot to mention that I did order it. I had ordered some other stuff so shippping didn't hurt too much. I have it already. I'm going to try to tackle it this weekend. I'll post back results..


Defiantly let us know how it goes! I am really curious. Thanks man!

Jase


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## ma2kster (Jun 4, 2010)

for the 05,06 model years there is a different setup. There are two sensors on the evap box: one is upstream of the evap, the other right after the evap. It is a pain to replace the one before the evap, almost impossible. later on, they discontinued this setup and there isnt an upstream sensor anymore and HVAC controller uses the temp reading from the outside temp sensor. A simple solution, but works. if you have the older setup with two sensors and the first sensor fails(25), it will be difficult...

see 25 and 29 below


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## daniel.ramirez (Nov 24, 2001)

1K0907543A was superseded in '08 by 1K0907543G ($44 ETKA says)


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## ma2kster (Jun 4, 2010)

daniel.ramirez said:


> 1K0907543A was superseded in '08 by 1K0907543G ($44 ETKA says)


That's the other thing in this HVAC mess Audi created for us: the old sensors (thermistors) were failing frequently. There are many cases of sensors being replaced by dealers (mostly MKV). they now have a new sensor, and is less likely to fail. I replaced all sensors with their successors, there are 6 or 7. The only sensor i kept is the one before the evap (it was impossible to get to)


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## neu318 (Feb 18, 2003)

After removing my glovebox last night and searching around the very tight area, I did not find the sensor. I'm guessing this has been removed for 2006 and above. I saw two other sensors before the air event on the passenger side and before the lower vent where air flows to your feet.


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## ma2kster (Jun 4, 2010)

neu318 said:


> After removing my glovebox last night and searching around the very tight area, I did not find the sensor. I'm guessing this has been removed for 2006 and above. I saw two other sensors before the air event on the passenger side and before the lower vent where air flows to your feet.


sensor (29) is common on all variations, BUT sensor (25) seems to be discontinued starting at some VIN split in 2006. Not having sensor (25) is a good thing 
sensor (29) is an essential sensor, it measures the temperature of the air coming out of evap. Too cold would mean icing up; so, sensor (29) looks for the optimum temperature (about 3 - 4 celcius) and helps adjust compressor output accordingly. if sensor (29) goes bad, one would likely get inefficient output from the compressor.


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## neu318 (Feb 18, 2003)

ma2kster said:


> sensor (29) is common on all variations, BUT sensor (25) seems to be discontinued starting at some VIN split in 2006. Not having sensor (25) is a good thing



I could not find sensor 29. I'm assuming that's where the Air filter goes. Correct? Could that sensor have been discontinued as well?


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## ma2kster (Jun 4, 2010)

neu318 said:


> I could not find sensor 29. I'm assuming that's where the Air filter goes. Correct? Could that sensor have been discontinued as well?


sensor (29) is definitely there. it can be tight/hidden, but it is definitely there. it is upstream of the cabin filter>
http://www.audi-portal.com/en/diagnostic/sensors_17061.html


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## neu318 (Feb 18, 2003)

ma2kster said:


> sensor (29) is definitely there. it can be tight/hidden, but it is definitely there. it is upstream of the cabin filter>


Damn, I couldn't find it. I guess only way to reach it is by taking the dash off which I will not be doing.


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## ma2kster (Jun 4, 2010)

neu318 said:


> Damn, I couldn't find it. I guess only way to reach it is by taking the dash off which I will not be doing.


No need to take the dash out. I think i removed the glove box, and the cabin air filter and it was visible. see link below too.

http://www.audi-portal.com/en/diagnostic/sensors_17061.html


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## neu318 (Feb 18, 2003)

ma2kster said:


> No need to take the dash out. I think i removed the glove box, and the cabin air filter and it was visible. see link below too.
> 
> http://www.audi-portal.com/en/diagnostic/sensors_17061.html


I did that too but didn't see it. Looking at the diagram I can't even begin to understand where it is located. If I have time this weekend I'll take it apart and look again. I'll take pictures this time.


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## neu318 (Feb 18, 2003)

Contacted ECS to see if they can tell me where the sensor is. All they could tell me was that it was underneath the cabin filter.  I did not see anything last night. Guess i'll have to keep looking.


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## 2006_A3_2.0T (Jan 11, 2013)

neu318 said:


> Contacted ECS to see if they can tell me where the sensor is. All they could tell me was that it was underneath the cabin filter.  I did not see anything last night. Guess i'll have to keep looking.


any update on this??


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## neu318 (Feb 18, 2003)

Yes. Sorry I forgot to update. I finally found the sensor. It's located behind the passenger kick panel next to the center console. Had to remove two small bolts to be able to lift it out if the way a little. After replacing the sensor the problem is still there. It maybe cools a little quicker but does not fix the problem. Sorry for the bad news. I'm in the same boat you are. I'd hate to have to replace the compressor. Last thing I want to check is the refrigerant level. Have to find someone to check that for me.


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## 2006_A3_2.0T (Jan 11, 2013)

Thanks, on a side note: forum users reported that refilling or replacing the refrigerant, or changing the refrigerant valve didnt solve the problem. 
The only working solution is new compressor and drier.
It costs 420 dollars at ebay the Sanden unit. Link on my otjer thread. 
I mighy do it but its last priority on my list. G/L



neu318 said:


> Yes. Sorry I forgot to update. I finally found the sensor. It's located behind the passenger kick panel next to the center console. Had to remove two small bolts to be able to lift it out if the way a little. After replacing the sensor the problem is still there. It maybe cools a little quicker but does not fix the problem. Sorry for the bad news. I'm in the same boat you are. I'd hate to have to replace the compressor. Last thing I want to check is the refrigerant level. Have to find someone to check that for me.


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## neu318 (Feb 18, 2003)

2006_A3_2.0T said:


> Thanks, on a side note: forum users reported that refilling or replacing the refrigerant, or changing the refrigerant valve didnt solve the problem.
> The only working solution is new compressor and drier.
> It costs 420 dollars at ebay the Sanden unit. Link on my otjer thread.
> I mighy do it but its last priority on my list. G/L



Yeah, that's what I'm worried about. Thanks for the info. I may have to do this soon since summer is approaching and humidity here in FL is always above 90% lol.


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## mike3141 (Feb 16, 1999)

I'm not sure how much effect it has but there's also a temperature sensor in the A/C controls. There's a little fan that sucks interior air through the little grate in the middle of the controls past it. Someone on one of the A3 boards had the fan fail and discovered that it's a separate part. I assume the controls use that temperature to regulate the heating/cooling and fan speed.


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