Heat exchanger in Roomster 2010

[Pini]

Hi all, 

Happy to see your assistance to all problems here! 

 

Iv'e got a Roomster 2010 1.6 petrol. 

My heat air conditioner doesn't work. Cooling works fine. 

 

Tring to figure it out, i opened the big plastic unit that holds the gear handle & the 12v socket and arrived to the heat exchanger. 

Anyway, got to realized that my heat exchanger has blown up and it's leaking (what explains why water in engine dissappears without any visible leakage + why my airbug ECU shorted out).

 

In short, 

I want to fix the heating, can someone please provide any data if leaking heat exchanger can cause cold air to flow while the temp button set to highest temp. Or is there any electronic heating unit that does the heat? 

 

Actually, 

I can't really understand this heat exchanger issue - if hot water flows thru it, why cold air flow?? What is all about? hot water VIA radiators gives hot air!

 

Confused.

 

Very appreciate your help. 

[aubrey]

There is a water radiator, called the heater matrix, which uses the hot engine water to provide hot heating. Have you got climatronic or climatic air conditioning ?

The only electrical items for the heating is the fan, and the various flap and actuator motors if full climatronic.

The hot engine water flow is controlled by a flexible cable (climatic) or an electronic servo motor (climatronic)

[Pini]

11 hours ago, aubrey said:

There is a water radiator, called the heater matrix, which uses the hot engine water to provide hot heating. Have you got climatronic or climatic air conditioning ?

The only electrical items for the heating is the fan, and the various flap and actuator motors if full climatronic.

The hot engine water flow is controlled by a flexible cable (climatic) or an electronic servo motor (climatronic)

Aubrey, thanks! 

You are great helper! 

 

I have climatic air conditioning and not climatronic. 

 

Regrad the flexible cable that controls the hot water flow - can you guide me where it's located? 

And how to verify that he works good? 

 

Thanks again! 

[KenONeill]

@Pini - Since you have air con, the term "heat exchanger", whilst an accurate description of the heater matrix, is likely to mislead, since "heat exchanger" is normally used of the air conditioning radiator mounted next to the engine radiator.

[Breezy_Pete]

Engine coolant flows through the heater matrix all the time.

Depending on temperature selected more or less of the incoming air is routed through this pathway, or bypasses it.

The motor and potentiometer that control this airflow directing may be malfunctioning.

[Pini]

@KenONeill - thanks for the info.
 I searched the component in Ebay and that was the name it gave.

 

@Wino

which motor\potentiometer did you mention?

I checked the air conditioner control unit and it seems ok, all works fine..

is there any heat-sensor that decide when to bypass un-bypass heater matrix?

 

[Breezy_Pete]

6 hours ago, Pini said:

which motor\potentiometer did you mention?

It's called the Temperature flap control motor, known as V68 in the circuit diagrams and VCDS, it has a potentiometer coupled to it within the same plastic housing, known as G92.

Both are wired to the air conditioning control unit.

 

Physically it's mounted on the left side of the air distribution housing; see item 27 here: https://skoda.7zap.com/en/cz/roomster/ro/2010-481/8/820-820010/

 

There is a temperature sensor within the air conditioning control unit that measures the cabin temperature.

 

If you search this site for V68 motor fault you may find some info that will help you to check if it is working correctly.

[aubrey]

There must be different versions, some with motors and others more manual. Mine has 2 flexible shafts. One from the air output choice knob (windscreen, feet, dashboard) and the other flexible shaft from the temperature knob.

[Breezy_Pete]

@aubrey non-aircon version?

[aubrey]

I've got Aircon, it a 2007 Roomster 3. I'm actually wondering now if I getting muddled between my Roomster and my son's 2012 Fabia. I've removed and refitted the heater controls on both.

I know my Roomster 100% has the airflow outlet choice flex shaft as I fitted it one turn out of sync first. The gearing gives 2 shaft turns to 1 knob turn and the output place was upside down on my 1st attempt. I had to unclip it, turn the control knob 180° and reattach.

Edited 26 December, 2018 by aubrey

[Pini]

On 25/12/2018 at 10:53, KenONeill said:

@Pini - Since you have air con, the term "heat exchanger", whilst an accurate description of the heater matrix, is likely to mislead, since "heat exchanger" is normally used of the air conditioning radiator mounted next to the engine radiator.

Hi @KenONeill, guys,

I didn't mistaken with my terminology regard the heat exchanger.. 

It is indeed my heat exchanger that blown - why? 

Because if i remember correctly, when i opened the case i didn't see the heat matrix at all! 

Is it make sense? There are models of roomster without heat matrix? 

 

20 hours ago, Wino said:

It's called the Temperature flap control motor, known as V68 in the circuit diagrams and VCDS, it has a potentiometer coupled to it within the same plastic housing, known as G92.

Both are wired to the air conditioning control unit.

 

Physically it's mounted on the left side of the air distribution housing; see item 27 here: https://skoda.7zap.com/en/cz/roomster/ro/2010-481/8/820-820010/

 

There is a temperature sensor within the air conditioning control unit that measures the cabin temperature.

 

If you search this site for V68 motor fault you may find some info that will help you to check if it is working correctly.

Wino, 

I think it doesn't related to motor, why? Because today i tried to move the temperature button from coldest to hotest and i listened quitly - there is a noise of motor working to move some flap when i did it. 

 

So, my intuition guides me ragard something electronic.. 

Cought my eye the temp. Unit that you mentioned (27 in the site). 

 

Also cought my eye items no. 35A and 35B - the "sense" units. 

Maybe can you indicate where they are located? 

 

I want you to realize the situation even further :

My dad drove without water -> heat exchanger blows-> water leaks -> airbag ECU getting short.. 

 

You know what i mean? It has to be something that related to water and electricity near the heat exchanger.. 

[Breezy_Pete]

Item 2, heat exchanger is the heater matrix, the only component in the system that has engine coolant running through it. All Roomsters will have one.

The heater flap motor (or the associated potentiometer, the position feedback system) can become unreliable in operation, moving to incorrect positions compared to what is requested, before they stop moving at all. So just because you hear it moving, doesn't mean it is behaving correctly all the time.

It could be that water vapour escaping from the air distribution housing after the matrix leak has got it into a few places and caused problems.

 

 

Evaporator temperature sensor item 35A can give problems too, but will only affect cooling, not heating.

 

Footwell vent temperature sensor(s) item 35B could cause trouble if they were giving bad information.  Find it/them (somewhere in the footwell vent pathways) and disconnect them, and see if the problem goes away?

 

 

A VCDS scan would tell you a lot. Have you replaced the heater matrix yet?

 

Edited 26 December, 2018 by Wino

[Pini]

yes, you right - I confused with auxiliary heater - this one for sure I haven't there.. only the Heat Exchanger.

 

tommorow i will search those units and update here.

 

BTW,

i do have VCDS software + ODB plug.

a log can assist here?

[Breezy_Pete]

2 minutes ago, Pini said:

do have VCDS software + ODB plug.

 

Scan for fault codes in the HVAC module.

[Pini]

@Wino

sent you in private message.

[Pini]

Address 08: Auto HVAC        Labels: 6Q0-820-045.lbl
   Part No: 5J0 820 045 
   Component: Klimaanlage        X0850  
   VCID: 62CA9214EE4FB056FC-5072

No fault code found.

for those who track..

 

no error in HVAC.

 

any ideas?

[Breezy_Pete]

If the air is flowing through the correct pathways, and there is no heat, the only other explanation I can think of is that there is no coolant flow through the matrix.  It may be airlocked.

 

I think you have to replace the leaking matrix first anyway, then see if problems remain after that.

[Pini]

@Wino, if for instance one of the temp sensors were malfunction - I should see it in the VCDS soft.? 

[Breezy_Pete]

You may be able to spot a temperature which seems very improbable, via measuring blocks. Temperature sensors can give very wrong readings without triggering a fault code, because the possible real range of temperatures is so large.

[Pini]

@Wino

scanned the measured temps at HVAC unit.

attached in the log.

 

temp. button set to highest, fan-3, direction air flow - passengers.

 

can you advise what could be the problem? 

log for Wino.txt

[Breezy_Pete]

No idea.  Replace the leaking matrix then see how things go.