# Cold Air from Cabin Air Vent (solution - flush out heat exchanger) [added to TOC]



## Jorgsphaeton (Sep 8, 2009)

I think I've got a problem; the air from the left vent in the middle of the dash stays cold in every condition, what could be the problem, or is it normal???

any suggestions?

thanks
Jorg


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## Irish Phaeton (Sep 6, 2010)

No doubt you have tried, but "Reset" the AC system. I never did figure out what the little red/blue buttons under the vents do.
Regards
Hugh


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## Jorgsphaeton (Sep 8, 2009)

yes tried reset several times, no result.
red gives you hotter air to your face then other body parts and blue cooler air to keep you a fresh mind for driving 
other ideas for the problem?


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## WillemBal (Nov 20, 2010)

Hi Jorg,
It sounds like an unusual problem. Given the huge amount of motors, fans and flaps for controlling both air temperature and flow velocity, possibly one of them got stuck, i.e. an air flap stays in the same position all the time.
The problem can be best diagnosed by means of a diagnosis tool, such as a VAS5051 (dealer) or by means of a VCDS cable, connected to a laptop.
The HVAC controller has a number of additional tests to check the operation of all of its components. Each flap has a position encoder, which can be read by a diagnostic tool.
Once you know which component is not responding properly, it is possible to find out where it is located by means of the part number or code in the electric diagram.

Willem


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## Jorgsphaeton (Sep 8, 2009)

Just ordered VAGCOM, so we will see, maybe somebody got the same problem, I investigated the design of the aircon and it is really a sophisticated piece of technology.
I hope I can fix it myself or find the problem, the shop will cost me a lot of money if they have to search for the problem, I think.

Nice to meet a dutch enthuasiast, maybe we can meet some day to discuss the car, are there other dutch enthuasiasts, as you know?

thanks Jorg


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## WillemBal (Nov 20, 2010)

Jorgsphaeton said:


> Nice to meet a dutch enthuasiast, maybe we can meet some day to discuss the car, are there other dutch enthuasiasts, as you know?


Hi Jorg,
There may be more Phaeton owners in NL who are enthusiastic about their P, but I only know one friend who has a W12 (he will never sell it). Unfortunately, there are not so many of them member of this great forum, just you and me and perhaps 1 or 2 others.
Yes, it sounds good to meet once and have a chat about all those things we are doing to keep them rolling! Where exactly are you located?

Willem


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## Jorgsphaeton (Sep 8, 2009)

In Valkenswaard near Eindhoven.
I got a 2003 V8, and I like it a lot, this is my dreamcar from the introducing of the phaeton.
unfortunately, this has been a bad year: problems with a shudder while braking, changed rotors and pads two times, all of them, the dealership couldn't find the problem, and they said the control arms were ok, changed the wheal bearings and hubs, for that same problem, and afterall I let them change the control arms in front and back on my costs and that was the problem. In the mean time the trunklid didn't work anymore, dealership changed the trunklid controller and slave controllers and the wiring. the wiring was broken and also damaged the controllers.
And I think my radiator is leaking, sometimes the front of the car under the radiator is wet and leaking, the strange thing about it is that it is sometimes. I think that will be fixed when changing the timing belt. Before no problems. it is a high mileage car 205.000 km so of course it will cause some problems. and I drive a lot in Belgium, and they really have bad roads, when raining the little stones from the bad road are ruining my radiator, I already added some race mesh to protect my radiator a bit.

Maybe we can arrange a get together for all dutch members and friends?

Jorg


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## Jorgsphaeton (Sep 8, 2009)

*Back to the problem*

Back to the problem:
Is I see correctly the left heat exchanger stays cold; left one is 16 to 29 degrees and the right goes to 50 degrees when all the settings, left and right are the same, everything I do I can't get the left heat exchanger to a higher temperature. How does the heat exchanger work, is it just a radiator?
is the engine coolant going through a valve?
any other suggestions?

thanks jorg


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## Jorgsphaeton (Sep 8, 2009)

the strange thing is; only the left center vent is cold all the others are hot as also the left chest vent near the door, and no faults in VCDS????

thanks Jorg


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## Jorgsphaeton (Sep 8, 2009)

anybody who can check the temperatures of his/her heat exhangers when all settings of the AC are the same for both sides? you need vagcom for it.
both valves are opening and closing correctly but I see that the left heat exhanger is colder than the right one, but the strange thing is, at the most left vent I get hot air just like all the right ones, except the left center vent is cold. I thought that the most left vent gets his hot air from the left heat exchanger, so it should be heating up?? Vagcom says it is only max 20 degrees while the right one is 50 degrees. I don't get it anymore, is it a flap for controling the hot or cold air or is it the heat exhanger that doesn't heat up enough or something else????

jorg


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## PanEuropean (Nov 3, 2001)

Jorg:

If the far left vent is emitting air at the desired temperature, but the center left vent is always cold, I am pretty sure that indicates a problem with the damper door system (the valve that mixes cold air and warm air to achieve the desired temperature being delivered from the vent), not a problem with the functionality of the heat exchanger.

You may want to experiment by manually setting the air delivery options to defrost, mid-level, and footwell, then seeing if the same pattern is evident.

Before you go any further, I strongly recommend that you get a copy of the Self-Study Guide #271, which is "Phaeton Heating and Cooling". Send me a private message or an email and I will forward these to you - they are far too big (about 8 megs) to post here on the forum. I can send you both an English and German language version. There is probably a Dutch version out there, you might be able to get it from your VW dealer if you show up with a USB memory stick and ask nicely.

Michael


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## Jorgsphaeton (Sep 8, 2009)

thanks for the advice, but why is the left heat exchanger colder then the other, is that how it used to be? I found a self study is it the same as yours? http://www.volkspage.net/technik/ssp/ssp/SSP_271.pdf
and if it is one aof the valves how can I fix them, should I open up the whole dash?

thanks
jorg


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## WillemBal (Nov 20, 2010)

Hi Jorg,
Before trying to dismantle the dash, which is quite a hefty job, please use the test program which is given in the VCDS program. You can find it by selecting the HVAC controller in VCDS, then look for the test program which is given in the right column of the listing of the various actions which can be performed. I described the method in more detail in a related thread about a problem with louvre vents. But I can't find it because I am in Australia right now where public internet is literally charged by the byte. The test sequence itself consists of well over 100 tests, where all flaps, motors and louvre vents are opened and closed. The test results are given in the form outputs numbers which are coming of the corresponding encoders. An encoder is basically a translation of the position into a number, for instance 0 to 255. If there is a failure of one of the components, you would see this as the corresponding position code then does not change while performing the test.
The final aim is to localize the defective component prior to dismantling the dash. Without knowledge about which part is defective prior to dismantling the dash, it will be quite impossible to find the defective component, I'm afraid.:facepalm:

Willem


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## Jorgsphaeton (Sep 8, 2009)

ok I will give that a try. I can't find that louvre vent thread either?

thanks Jorg


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## WillemBal (Nov 20, 2010)

Found it!
Ventilation-vent-stays-open


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## boessie (Oct 30, 2011)

*ssp*

Hi Jorg,
I'm new to this forum and don't own a Phaeton (yet).
I have a lot of self study programs written in Dutch. The most interesting for you are:
248 W-motorconcept
250 Motormagement W12
270 Phaeton
271 Klimaatregeling en verwarming
272 Elektrische installatie
273 Comfortelektronica
274 Infotainment
275 Luchtvering
276 Adaptive cruise control
277 Onderstel
303 V10 TDI

The good news is that I live close (+-20 km) to your place in Overpelt, Belgium.
You can always come by with a USB-stick and have a drink :beer:also.
For my adress send an email to gunther punt boes apestaart skynet punt be.

Greetings Gunther


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## Jorgsphaeton (Sep 8, 2009)

thanks for the self-study, we should make an appointment soon.

I used VAGcom to test all the outputs and all are giving an output when testing.
and no fault codes either.

today in the rain I noticed that only the left part of the windscreen got damped so it is clear that the left part is not getting any hot air.
How can I re-adapt all the flaps in the HVAC, maybe that could work?

thanks Jorg


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## WillemBal (Nov 20, 2010)

Jorgsphaeton said:


> today in the rain I noticed that only the left part of the windscreen got damped so it is clear that the left part is not getting any hot air.
> How can I re-adapt all the flaps in the HVAC, maybe that could work?
> thanks Jorg


Hi Jorg,

To re-learn the flap positions, fire up VCDS, select the HVAC module (08), next select Adaptation. When this fires up, you see some instructions. Follow them and for the next 30 to 60 seconds you will see and hear some bizarre things going on, louvre vents opening half way etc. After that, the positions have been re-learnt and stored.

To improve the defrost function, please shut down the rear HVAC. During normal operation in cold weather, both V212 and V211 are fully opened, which means that a lot of hot air is flowing to the rear of the car.
In addition, no air will flow through the perforated dash panel. About 25% of the air is used for defrosting the windshield, which is flowing into the cabin via a small gap between the windshield and the perforated dash panel. Only when you hold your hand against the windshield, you can actually feel the hot air. I suggest that you activate the defrost function, which will close the footwell flaps and open up the windshield defrost flap 100% (V107). With VCDS, you can check this with MVB, via group 10. I expect that you see something like 210 for set value, spec value and maximum position, and 110 or less for minimum value.

Btw: There are no separate left & right sides for windshield defrosting. There is something like "front left defroster and chest vent V200", but I think this one will only defrost your door window.

Regards,
Willem


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## Jorgsphaeton (Sep 8, 2009)

the heat exchanger on the left stayed colder than on the right, I flushed the left heatexchanger and that was the solution. I used the two hoses on the HVAC flap controller in the front of the windshield to flush the heatexhanger with water.

thanks
Jorg


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## PanEuropean (Nov 3, 2001)

Jorgsphaeton said:


> the heat exchanger on the left stayed colder than on the right, I flushed the left heatexchanger and that was the solution. I used the two hoses on the HVAC flap controller in the front of the windshield to flush the heatexhanger with water.


Wow, that is quite fascinating to discover that the cause of the problem was mechanical (partially plugged heat exchanger) rather than some form of electrical or electronic gremlin (a damper door not opening properly, or a signal to a vent not being acted upon.

I'm going to put this post in the FAQ, because I think we might seem more of this same problem in the future as the cars get older. To my knowledge, there is no defined schedule for changing the coolant or flushing the system out (although there was a campaign many years ago - 66C4 criteria 5 - that identified problems with blocked heat exchangers, and provided a solution). I think, though, that as the first batch of cars now reach their 10th birthday in 2012, it might become necessary for owners to occasionally flush out the cooling system in order to solve similar problems.

Attached below is a copy of the ROW (rest of world) campaign 66C4. This campaign did not apply to NAR (North American Region) cars, but all the items in the campaign - with the sole exception of criteria 5 - were called out by separate, independent bulletins put out by VW of North America. 

By now, this campaign should have been carried out on all affected ROW vehicles (your dealer can easily determine if this campaign applied to your car, and was carried out on your car, just by checking the service record system). That notwithstanding, the information in criteria 5 might be of use to anyone who needs to flush out heat exchangers in the future.

Michael


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## Jxander (Aug 5, 2008)

Michael & All:

I doubt the heater cores or heat exchangers would ever plug if the cooling system was maintained by an occasional flush and coolant replacement. However, doing the fluid exchange properly is necessary. One thing to make sure is that the car is warmed up and the heater is on the max temperature. That way the heater control valves will be open and the flush/exchange will be complete. If the heater is not on, the heater control valves will be closed or pinched-off and it will not be part of the flush and coolant replacement. The other catch is to make sure all air is out of the cooling system. This is more likely to happen if the heater exchangers are integrated into the process.

How long coolant will perform well is a topic I'll avoid - since I have no good answer. However, I personally will never have the same coolant for as much as 10 years or 100k miles. Changing coolant is not that expensive. 

Jim X


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## Gammaray (Aug 30, 2009)

*Cold Air déjà vu*

To Jorg or forum,

I now have the same problem w/my left center vent as you once did. Is this something that can be fix via do-it yourself? Or do you recommend dealer participation?


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## Gabs08PHTN (Jan 6, 2011)

Hi,
I think that your best bet is to either purchase a VAG COM scanner, or borrow one. With that tool you can easily determine what is wrong in the HVAC system of your phaeton. As mentioned in one of the posts above, phaetons feature several servomotors to control the air distribution, so it could well be that one of those servomotors is faulty and it is not a heat exchanger related issue.

Gabriel


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## Saeid (May 29, 2013)

I have the same problem with my driver side heat exchanger as I get cold air in driver side and proper temp on the passenger side, this happens when the car is at below 1500 RPM once it passes 2000 RPM, I get heat on the driver side also. I am assuming that the heat exchanger is partially clogged and does not allow coolant to travel in the heat exchanger at low pressure and at higher RPM the flow is faster and that is why I get heat and loose heat as RPM is reduced to below 1500. I will flush the heat exchanger and report back


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## Paximus (Aug 26, 2011)

Hi Saeid, 

Welcome to the forum!

I hope you have some luck identifying the problem. All information is welcome here, as you can see.

Chris


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## PanEuropean (Nov 3, 2001)

Saeid said:


> ...I am assuming that the heat exchanger is partially clogged and does not allow coolant to travel in the heat exchanger at low pressure and at higher RPM the flow is faster and that is why I get heat and lose heat as RPM is reduced to below 1500.


Hi Saeid:

I think you have made an accurate analysis of the most probable cause of the problem. But, before you start taking things apart to do the flush, run a diagnostic scan and see if there are any fault codes stored that describe failures of the various flaps, vent motors, and so forth in the HVAC system (controller 08). Although I agree that a plugged heat exchanger is the most probable cause of your difficulty, it is possible that you might just have an inoperative flap or vent door in the heater core, and the correlation between RPM and functionality is actually a correlation between vehicle speed (pressure differential between the air intake and the cabin air pressure) and heating performance, not RPM and heating performance.

Michael


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## Gammaray (Aug 30, 2009)

Hi Saeid/Forum,

I have the the same issue now with my Phaeton. Blowing cold air from the driver side vent and a high rpm heat start. I had the system/heater core flushed and also took it to a VW dealership. They could not fix. They needed more diagnostic time which adds up quickly. Did you ever find or fix the problem w/your Phaeton?


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