Heater Cold One Side - SOLVED

[KGCali]

In my T5.1 with Climatronic Aircon my wife always complained the heating on the passenger side was cold unless on Max or Auto turned off, especially on her feet whilst mine was fine. I looked into this a while back but then forgot all about it until I purchased an OBD11 Pro diagnostic tool during lockdown to have a play with. Whilst scanning the Aircon system I noticed that the temperature on the footwell vent sensors never moved, one fixed at 58C and the other at 87C whilst the front vent sensors worked fine.

I had a search of YouTube and found a useful video on how this type of sensor worked and then found the California part number 4B0820539 and purchased two used ones from eBay for £2.10 each, a bargain. Tested the replacement ones with a multimeter and haidryer and all worked fine!

Found another useful YouTube video on fitting a T5 carpet which details how to remove the trim under the gearstick which gave access to the driver's side temperature sensor and just a few clips and screws to remove the passenger side lower trim, see YouTube heater resistor video, to access the passenger side temperature sensor.

About 30 minutes to remove both sides, 5 minutes to replace the sensors and the same again to refit the panels using a Torx T20 bit.
Plugged in the OBD11 Pro and started the engine to warm up and now both footwell vent temperature sensors are working fine and warm (or cold as selected) air on both sides!

 

[Frafra]

Great. Thanks for all of that research in one place. Best!

 

[Perfectos]

What a great informative post.

Good on you for sorting out the issue, many would have ignored

 

[Sir Alvin Byron]

Hi, thanks so much for informations and photos!
I think to have the same problem.
As I saw that's so easy to replace this weekend I'll invert sensors to understand witch one is broken

 

[Sir Alvin Byron]

Please let me know what ODB tool do you have bought, perhaps this one?
OBD11 Pro diagnostic tool

 

[KGCali]

Please let me know what ODB tool do you have bought, perhaps this one?
OBD11 Pro diagnostic tool

View attachment 88279

Yes, that's one OBD Eleven tool I have but the newer NextGen version and then purchased the Pro license online direct from OBDeleven when they were still offering a lifetime license, paid for itself many times over. Good luck with your heater....
OBDeleven Starter Edition Next Generation Professional OBD2 Bluetooth Diagnostic Scan Tool Fault Clear For Android and IOS https://www.amazon.co.uk/dp/B07HCGJ8ST/?tag=eliteelect-21

 

[ipap]

Hi, I know this is an older thread, but I am having similar problems.

Cold air on passenger side, but only if the selection is on upper vents. When upper and lower or auto, it blows nearly as warm as the drivers side.
I have replaced the footwell vent sensor on the passenger side, which stopped it blowing cold all the time.

The question I have is on a T5.1, where is the passenger side "Left Front Vent Temperature" sensor that is noted in the live data screen shot above located in the vehicle?
Many thanks for the great guide on this.

 

[GrumpyGranddad]

Have you tried resetting the flaps?

 

[KGCali]

Hi, I know this is an older thread, but I am having similar problems.

Cold air on passenger side, but only if the selection is on upper vents. When upper and lower or auto, it blows nearly as warm as the drivers side.
I have replaced the footwell vent sensor on the passenger side, which stopped it blowing cold all the time.

The question I have is on a T5.1, where is the passenger side "Left Front Vent Temperature" sensor that is noted in the live data screen shot above located in the vehicle?
Many thanks for the great guide on this.

I think the front vent temperature sensors are part 11 on this LLLParts diagram and Google link ...

Google

 

[ipap]

I think the front vent temperature sensors are part 11 on this LLLParts diagram and Google link ...

Google

View attachment 116172

Wow, thanks @KGCali, I spent an age yesterday looking for a diagram like that and failed!
Thank you for everything in this thread and the super fast reply. I will update the thread when I get back under the dash and investigate.

 

[ipap]

Ok, so I have found the upper vent temp sensor and managed to change it, and evverything is working.
Seeing as this thread was the starting point, I wanted to add my knowledge to this thread for future searchers of this issue.

Firstly, to determine it was the tope even sensor, I had to run just the top vents, when they were on 26 on the dial, I was just getting cold air. If I selected head and feet on the selector and had it still at 26, I started getting some heat out of the face vents. I assume this was because it was averaging the temp from both face and feet sensors.

Anyway, I digress. The sensor is on the side of the heater unit behind the stereo, but reachable from behind the glovebox, just... It is very tight and difficult to see or get to.

It is behind the metal plate in this photo 1.

Close up in photo 2, you are looking at the white piece, which is the sensor and the black connector in the bottom of it

Also just visible behind the stereo on the left side in photo 3.

You will need to pinch both sides of the connector and pull it downwards, but it will catch on a item below, so rotate the sensor forwards a bit to make removal possible.

Once the connector is removed, rotate the sensor all the way forward, 90 degrees. Removinging the sensor requires a lot of wiggling.

Installation is the reverse of removal and also very tricky.

If anyone has any questions, please feel free to ask for more details on this thread and I will respond.

 

[KGCali]

Glad you got it sorted and good info for the forum, that's what this site is all about
Would the sensors be accessible if you took the radio out as that's quite easy?
Where did you get the replacement sensors from?

 

[ipap]

Glad you got it sorted and good info for the forum, that's what this site is all about
Would the sensors be accessible if you took the radio out as that's quite easy?
Where did you get the replacement sensors from?

Picture 3 is looking in with the radio out, you can see the sensor is on the right, it is the white bit above my fingers in the gap at the back. Behind the radio is part of the aircon unit, where the air is diverted and so it is only accessible from the side but I was able to put a long screwdriver through the gap that is visible in picture 3 to help unclip the connector and help align the connector for reinstalation.

The sensor was from a eBay vendor:

Interior Air Temperature Sensor fits SKODA RAPID 2012 on Lucas 4B0820539 Quality

Interior Air Temperature Sensor fits SKODA RAPID 2012 on Lucas 4B0820539 Quality | eBay

AUDI A6 C6 (4F2) 2.0 TDI Saloon Diesel 11/2008 03/2011 FWD 16 170 125. Fitting Position: Footwell. AUDI A6 C6 (4F2) 2.0 TDI Saloon Diesel 07/2004 03/2011 FWD 16 136 100. AUDI A6 C6 (4F2) 2.0 TDI Saloon Diesel 07/2004 10/2008 FWD 16 140 103.

www.ebay.co.uk

£19.02 - a bit more than you paid but it works, so all good with me. It looks like the part is a standard fitment on the entire VAG range.

 

[Vanster]

Hi all, new to the forum but also having issues with passenger side heating on my 2013 T5.1 Multivan with Climatronic.

Having issues with both front vents and footwell, ie not limited to one or the other. Find it curious that both sensors would go at same time.

Suppose I needs to get a code reader or have codes read before going at the sensors.

Any ideas what could be the issues beyond the sesnors? (still thinking odd for both to go at same time)

 

[GrumpyGranddad]

Hi all, new to the forum but also having issues with passenger side heating on my 2013 T5.1 Multivan with Climatronic.

Having issues with both front vents and footwell, ie not limited to one or the other. Find it curious that both sensors would go at same time.

Suppose I needs to get a code reader or have codes read before going at the sensors.

Any ideas what could be the issues beyond the sesnors? (still thinking odd for both to go at same time)

Worth trying a reset in the first instance.

 

[Vanster]

Thanks, forgot to mention I did that already to no avail. That pic is exaclty my Climatic unit.

I guess will need to either buy a reader or take it to a garage to be read. I could order two sensors and replace front and footwells but still am suspicious about both not working at the same time…

I am in Switzerland so also concerned about frozen windshield not defrosting on the passenger side when winter kicks in.

 

[ipap]

Thanks, forgot to mention I did that already to no avail. That pic is exaclty my Climatic unit.

I guess will need to either buy a reader or take it to a garage to be read. I could order two sensors and replace front and footwells but still am suspicious about both not working at the same time…

I am in Switzerland so also concerned about frozen windshield not defrosting on the passenger side when winter kicks in.

A good test is to put the tempt to max, when the car is warm and see if hot air comes out. When it is on max, the car puts out hot air without measuring the temp using the sensors.

If it does blow hot air, then it’s likely to be a sensor.

When mine had a sensor issue it was still able to blow how air on max temp through the system.

Hope that helps you narrow your problem.

 

[Vanster]

Thanks!

So on full temp “Hi” I only get hot on the driver side, passenger side remains cool, even in Max Defrost and “Hi” Temp only cold air is blowing on entire front passenger side.

Cold air flowing from passenger front vent, front side vent, footwell vent and windshield defrost vent.

On the driverside (lefthand drive) everything is warm.

It as as if there is a main hot air distribution to the passenger side that feeds all 4 vents and it is not getting warm air. Is there a main splitter or distribution valve/door?

I did the vent reset multiple times and no change.

 

[KGCali]

Thanks!

So on full temp “Hi” I only get hot on the driver side, passenger side remains cool, even in Max Defrost and “Hi” Temp only cold air is blowing on entire front passenger side.

Cold air flowing from passenger front vent, front side vent, footwell vent and windshield defrost vent.

On the driverside (lefthand drive) everything is warm.

It as as if there is a main hot air distribution to the passenger side that feeds all 4 vents and it is not getting warm air. Is there a main splitter or distribution valve/door?

I did the vent reset multiple times and no change.

Swap over one or more sensor from the driver to the passenger side and see if the situation reverses.

 

[Vanster]

Thanks, are there two on each side or more? From the threads above I gather there is an upper one by the radio and a lower one as described.

Would one bad sensor cause the entire side to go cold across all 4 vents?

 

[KGCali]

No, I only had a dead lower passenger side sensor which caused only cold air to the passenger side and foot vent, the top vent worked fine so I didn't need to change the upper sensor.
I'd swap the lower sensor over first as they're easier to get to.
Good luck.

 

[Vanster]

Thanks, I’ll give it a shot. Can you confirm there are only two sensors per side and they somehow control all 4 vents (front center, front side, footwell and windscreen defrost)?

The windscreen defrost I could imagine is always warm so the fact that it is also cold leads me to think its more an air valve to the passenger side that is not working.

Is there such a valve/door that controls the entire side?

 

[KGCali]

Thanks, I’ll give it a shot. Can you confirm there are only two sensors per side and they somehow control all 4 vents (front center, front side, footwell and windscreen defrost)?

The windscreen defrost I could imagine is always warm so the fact that it is also cold leads me to think its more an air valve to the passenger side that is not working.

Is there such a valve/door that controls the entire side?

Yes, only two sensors per side. Your issue could be the heater control flap servo motor not working but you'd need to scan your system with VCDS or OBD2 to diagnose that.

 

[Vanster]

Thanks, bringing it in for VCDS reading Wed am, cold and snowy here so cold defrost is a real problem……keep you all posted on outcome

 

[GrumpyGranddad]

Thanks, bringing it in for VCDS reading Wed am, cold and snowy here so cold defrost is a real problem……keep you all posted on outcome

You could use the diesel heater to warm up the van and defrost it?