Climate control - blowing hot all the time

Timmyo

Timmyo

Member
HI - the climate control unit in my 2003 TDi seems to be not responding to cabin temperature. Whatever temperature i set it to it seems to be pushing out warm air so it gets very stuffy and i have to open windows and turn it off.

The directional air flow buttons all seem to function ok, its as if its not detecting caboin temperature and responding accordingly. On Lo setting (which should blow out cold/air-con air? it si still pushing out warm air thoigh not as warm as if i have it set to say 22 degrees.

Any thoughts? Would swapping the entire climate control panel potentially sort this as I was thinking of looking for a less worn one in any case?
 
Timmyo said:
HI - the climate control unit in my 2003 TDi seems to be not responding to cabin temperature. Whatever temperature i set it to it seems to be pushing out warm air so it gets very stuffy and i have to open windows and turn it off.

The directional air flow buttons all seem to function ok, its as if its not detecting caboin temperature and responding accordingly. On Lo setting (which should blow out cold/air-con air? it si still pushing out warm air thoigh not as warm as if i have it set to say 22 degrees.

Any thoughts? Would swapping the entire climate control panel potentially sort this as I was thinking of looking for a less worn one in any case?
Click to expand...
It's likely to be caused by one of the control flaps, (there are five), within the HVAC being stuck. These flaps control the air flow, and importantly in your case, the mixing of warmed air and cold air, to give the required cabin temperature.
A scan of the HVAC will confirm it, and tell you which flap is the problem. Most likely failure is the servo motor that drives the flaps.
Screenshot_20250220-095539.png

Mac.
 
@PlasticMac I'm thinking of putting her in to my local independent VAG specialist for a service next week so will get them to run a diagnostic as i dont have capabilities for that.

@ThomasDitlev is that the little tiny grill at centre-top of the control module?...it does look a bit "fluffy" in there!
 
Timmyo said:
@PlasticMac I'm thinking of putting her in to my local independent VAG specialist for a service next week so will get them to run a diagnostic as i dont have capabilities for that.

@ThomasDitlev is that the little tiny grill at centre-top of the control module?...it does look a bit "fluffy" in there!
Click to expand...
You could look at the A2 Owners Club Free Scan Register. There maybe a member, not too far away who can help.
Mac.
A

Thread 'Free Scan Register'

This is a register of members who generously offer free scans for other members.

To arrange a free scan:

1. Click the pdf map in the footer and choose a location.
2. Cross reference the location number in the table below to identify the member.
3. Click on their username on the left, click 'Start conversation' to initiate a PM, request a free scan and arrange between yourselves.

Please note a free scan is not guaranteed, it may not be immediately convenient for the member.

Username​
Location
Notes​
@luzt
...
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This will be the V68 Temperature Flap Positioning Motor and most likely the potentiometer inside being corroded and getting stuck in one position. It is well documented on here. The usual trick is to cycle the temperature from hot to cold a few times on the control unit to see if that frees it up. Otherwise you can manually manipulate the cogs by removing the glovebox to get access but that's likely a temporary fix. I went this route (a few times) and it has just started playing up again.

I'm either going to get a new flap motor (not cheap) or tease open the existing one and clean up the insides if I can work out how to actually remove it :rolleyes:
 
Mine has done this a few times, normal solution is to drive home with the windows open and next time I start it's fixed itself. Interestingly, the heating is significantly hotter when it goes wrong than normal, which always led me to wonder whether normal is working correctly ...
 
Foghorn said:
This will be the V68 Temperature Flap Positioning Motor and most likely the potentiometer inside being corroded and getting stuck in one position. It is well documented on here. The usual trick is to cycle the temperature from hot to cold a few times on the control unit to see if that frees it up. Otherwise you can manually manipulate the cogs by removing the glovebox to get access but that's likely a temporary fix. I went this route (a few times) and it has just started playing up again.

I'm either going to get a new flap motor (not cheap) or tease open the existing one and clean up the insides if I can work out how to actually remove it :rolleyes:
Click to expand...
That sounds like a dash out kind of fun.
 
Foghorn said:
This will be the V68 Temperature Flap Positioning Motor and most likely the potentiometer inside being corroded and getting stuck in one position.
Click to expand...
lavandism said:
That sounds like a dash out kind of fun.
Click to expand...
Correct, this has ‘V68’ fault written all over it.
I’ve fixed this issue loads in the past year. Removing the dashboard isn’t necessary, but it’s a fiddly process riddled with pitfalls and is likely to cause headaches for anyone upon first attempt.
I have always managed to successfully repair the existing V68 electrical assembly, which saves ~£250 in parts.

Cheers,

Tom
 
timmus said:
Correct, this has ‘V68’ fault written all over it.
I’ve fixed this issue loads in the past year. Removing the dashboard isn’t necessary, but it’s a fiddly process riddled with pitfalls and is likely to cause headaches for anyone upon first attempt.
I have always managed to successfully repair the existing V68 electrical assembly, which saves ~£250 in parts.

Cheers,

Tom
Click to expand...
Thanks Tom, and everyone...Ive just set myself up with VCDS Lite so going to have a go at seeing if any fault codes show up. And perhaps at some point get it to you to be sorted! In the meantime I can live with being too hot and some days it does seem to behave more as it should (don't you just hate intermittent faults). Id be more worried if the heating wasn't working at all as I feel the cold and i live in Wales so we rarely ever need cold air-con!!

Could this be related to the fact that the temperature gauge seems to rarely climb above 65? My old A2s always ran pretty much bang on 90
 
Timmyo said:
Thanks Tom, and everyone...Ive just set myself up with VCDS Lite so going to have a go at seeing if any fault codes show up. And perhaps at some point get it to you to be sorted! In the meantime I can live with being too hot and some days it does seem to behave more as it should (don't you just hate intermittent faults). Id be more worried if the heating wasn't working at all as I feel the cold and i live in Wales so we rarely ever need cold air-con!!

Could this be related to the fact that the temperature gauge seems to rarely climb above 65? My old A2s always ran pretty much bang on 90
Click to expand...
Limp temp gauge is usually a sign of failed coolant temp sensor (059 919 501A), and/or thermostat (044 121 113).
Rather easily available elsewhere, but OEM are the ones that last longest and worth the extra.

You can check what temperature ECU is reading with VCDS-lite, it is one of the first measuring block groups (@PlasticMac should know precisely).
That should give you an idea if it is a sensor or a thermostat.

edit: though it blows inferno, so thermostat is definitely not stuck open hahahahhahahahah. must be a sensor then.
it's at the back of the engine, a green thumb with a connector, accessible from the top. open the coolant expansion tank to release pressure before you change it, unless you like pink glycol fountains.
 
The Engine/Coolant temperature sensor can be checked with VCDS, (other tools are available), from the Engine Controller, (01). Measuring Blocks, Group 001, Block 2. This is the sensor, (G62), the ECU uses, and is the most important. It is not the sensor the temperature gauge on the dash uses. They are electrically separate.
The Dash Gauge sensor can be checked from the Instruments Controller, (17). Measuring Blocks,
Group 003, Block 1. This is the sensor the dash gauge uses, and VCDS will show you the actual temperature the sensor is monitoring.
The dash gauge is driven by a processor, that "massages" the sensor output, such that the gauge is a very basic indicator only. Designed to make the driver feel relaxed. Will indicate 90C when the sensor sees anything between 80ish and 95ish.
The two reading on VCDS, one from the Engine Controller, the other from the Instruments Controller, should be very close to each other.
If they are different, you have to decide which is right. The best way of doing that is with a thermometer, ideally a contact or infra red type, from the engine outlet/top hose. The radiator is not a good guide, because the coolant there is, probably not at the same temperature as the engine. Remember, coolant only flows through the radiator when the thermostat is open, and the radiator's job is to cool the coolant.
The heat output from the cabin heater, and the way the car drives, should give you an idea of which VCDS temperature is correct though.
The two separate sensor are in a single unit. If you replace it, use OEM, genuine VAG. Aftermarket sensors can be of doubtful quality. Because the ECU uses it's sensor to control fuel/air mixture, it is a very important part.
If your not familiar with VCDS Lite, take a look here:
This is an interactive guide, and is exactly how it is on your laptop.
Mac.
 
PlasticMac said:
The Engine/Coolant temperature sensor can be checked with VCDS, (other tools are available), from the Engine Controller, (01). Measuring Blocks, Group 001, Block 2. This is the sensor, (G62), the ECU uses, and is the most important. It is not the sensor the temperature gauge on the dash uses. They are electrically separate.
The Dash Gauge sensor can be checked from the Instruments Controller, (17). Measuring Blocks,
Group 003, Block 1. This is the sensor the dash gauge uses, and VCDS will show you the actual temperature the sensor is monitoring.
The dash gauge is driven by a processor, that "massages" the sensor output, such that the gauge is a very basic indicator only. Designed to make the driver feel relaxed. Will indicate 90C when the sensor sees anything between 80ish and 95ish.
The two reading on VCDS, one from the Engine Controller, the other from the Instruments Controller, should be very close to each other.
If they are different, you have to decide which is right. The best way of doing that is with a thermometer, ideally a contact or infra red type, from the engine outlet/top hose. The radiator is not a good guide, because the coolant there is, probably not at the same temperature as the engine. Remember, coolant only flows through the radiator when the thermostat is open, and the radiator's job is to cool the coolant.
The heat output from the cabin heater, and the way the car drives, should give you an idea of which VCDS temperature is correct though.
The two separate sensor are in a single unit. If you replace it, use OEM, genuine VAG. Aftermarket sensors can be of doubtful quality. Because the ECU uses it's sensor to control fuel/air mixture, it is a very important part.
If your not familiar with VCDS Lite, take a look here:
This is an interactive guide, and is exactly how it is on your laptop.
Mac.
Click to expand...
legend you are, Mac
 
Thansk for the pointers. I'll have another go with the VCDS-Lite tomorrow....i tried today and it was trying to connect to the controllers but after 4 attempts kept saying couldnt connect. Could be me doing somehting simple wrong...i ran the Test function, and then Save which seemed ok
 
bretti_kivi said:
bit rate 9600 8 n 1, make sure you're using the correct USB / Com ports.
Click to expand...
Adding the A2OC HVAC label file is a good idea.
Timmyo said:
Thansk for the pointers. I'll have another go with the VCDS-Lite tomorrow....i tried today and it was trying to connect to the controllers but after 4 attempts kept saying couldnt connect. Could be me doing somehting simple wrong...i ran the Test function, and then Save which seemed ok
Click to expand...
Did you install, and manually configure, the, (USB to Serial), device drivers that are provided on the Ross-Tech website? If not, you should.
It quite likely that your laptop has allocated the default USB driver to the Gendan cable. This will not work.
The correct driver must be allocated to the cable. The correct driver, for Lite is the one Ross-Tech provide.
There is also an A2OC HVAC label file for Lite, which you should use too. It's here:
Thread 'Updated Label Files for VCDS Lite.' https://www.a2oc.net/community/index.php?threads/updated-label-files-for-vcds-lite.55908/
Mac.
 
PlasticMac said:
Adding the A2OC HVAC label file is a good idea.
Did you install, and manually configure, the, (USB to Serial), device drivers that are provided on the Ross-Tech website? If not, you should.
It quite likely that your laptop has allocated the default USB driver to the Gendan cable. This will not work.
The correct driver must be allocated to the cable. The correct driver, for Lite is the one Ross-Tech provide.
There is also an A2OC HVAC label file for Lite, which you should use too. It's here:
Thread 'Updated Label Files for VCDS Lite.' https://www.a2oc.net/community/index.php?threads/updated-label-files-for-vcds-lite.55908/
Mac.
Click to expand...
I downloaded some drivers from the Gendan website I think following instruction sheet that came with the cable (which i now seem to have mislaid)
 
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