How does the temperature control works with manual A/C (ClimaTIC not ClimaTRONIC)?  Is there a thermostat involved in the process or is it old-school mixing of outside air with conditioned air?

Most Octavia in the Uk come with climate control but my base model Australian version has the ordinary aircon fitted.

As I understand it the air passes over the aircon cooling matrix and the heater matrix (don't in what order) and then vents into the car.

You turn on the aircon and it kicks in to bring down the cooling matrix to a few degrees above zero to avoid ice forming on it and blocking up. Turning up the rotating temperature control knob merely increasingly more hot water into the heating matrix, which moderates the cool air temperature venting into the cabin, but this is really quite an inefficient way of doing things.

 

I run without the aircon on as much as possible but if the internal temp rises above comfort level then obviously I turn the aircon on and run at minimum fan speed which is usually enough for moderate conditions and turn up fan speed as required. That way it is surprisingly effective and economical at highway speeds.

When we hit our really hot 40+ deg C temps then the fan speed is set to high and re-circulate the air. The fan is quite noisy and intrusive then but unavoidable in those extreme conditions.

 

Very occasionally we experience relative high outside air temp and humidity (30+ and 80+%) in overcast conditions or at night and I have found that having the aircon on and even set at the lowest fan speed the air is too cold for comfort and have to turn up the 'heater' setting a bit.  The alternative is to manually turn the aircon on and off as required but that is too much faffing around even for me. That is the one time I miss the climate control which basically does that turning off/on for you.

 

In wet or humid conditions the only way to control internal humidity is to turn on aircon and heater with air recirculation also turned on.

 

With our local climate we generally get away with either just aircon or heater on. Climates with higher humidity (the UK can get very humid) have a greater need for climate control which does all that manual setting stuff automatically.

 

 

 

Edited 13 September, 20196 yr by Gerrycan

 

Just to add as a side point what i find a bit shocking, is the NEW VW Passat SE and SEL model have manual heating control, this is crazy for a car which comes with that RRP.

 

My understanding of the non climate control version is just that, there's no climate control, its just a heater with A/C with a dial.

 

 

Edited 13 September, 20196 yr by RickTT

I think it works like this.

Engine coolant is full time going through the heater matrix, no flow valve there. (Not sure there is for Climatronic either TBH)

100% of the incoming cabin air goes through the A/C evaporator, cooling as it does so if A/C is active; just passing through unchanged if not.

Then it is diverted in varying proportion by the heater flap motor (V68 I think) through the heater matrix. The more heat you demand, the more the flap is biased towards air passing through the matrix, the less heat you demand, the more is bypassing the heater matrix. 

 

 

 

 

2 minutes ago, Wino said:

Engine coolant is full time going through the heater matrix, no flow valve there. (Not sure there is for Climatronic either TBH)

100% of the incoming cabin air goes through the A/C evaporator, cooling as it does so if A/C is active; just passing through unchanged if not.

Then it is diverted in varying proportion by the heater flap motor (V68 I think) through the heater matrix. The more heat you demand, the more the flap is biased towards air passing through the matrix, the less heat you demand, the more is bypassing the heater matrix. 

 

That's more or less my understanding too.

 

SSP 513 (891143C?) shows a little of the HVAC side on a MK7 Golf (same platform as a MK3 Octavia) and certainly doesn't mention any valve for the heater matrix.

7 minutes ago, Wino said:

I think it works like this.

Engine coolant is full time going through the heater matrix, no flow valve there. (Not sure there is for Climatronic either TBH)

100% of the incoming cabin air goes through the A/C evaporator, cooling as it does so if A/C is active; just passing through unchanged if not.

Then it is diverted in varying proportion by the heater flap motor (V68 I think) through the heater matrix. The more heat you demand, the more the flap is biased towards air passing through the matrix, the less heat you demand, the more is bypassing the heater matrix. 

 

 

That probably explains why the air coming in through the vents, with aircon off and circular temp knob turned to coolest setting, is never as as cool as the outside air temp. Really annoying.

On the old 9N Polo/Mk1 Fabia platform, there's a temperature sensor inside the control panel that has a tiny fan pulling cabin air over it. I assume this is to give a feedback mechanism so that when the desired cabin temperature is reached, the heater flap motor can be re-adjusted as required to maintain that.  

 

 

1 minute ago, Gerrycan said:

 

That probably explains why the air coming in through the vents, with aircon off and circular temp knob turned to coolest setting, is never as as cool as the outside air temp. Really annoying.

 

Yes, a disadvantage of the full-time engine coolant presence is that there's inevitably heatsoak, even if the airflow is diverted away from the matrix.

On the plus side, there's no coolant bypass valve to spring leaks, which they often seem to on implementations that do use that strategy. 

I think the base model Yeti that I have just bought but not yet seen has manual aircon & not Climatronic, I will soon find out the difference but if anyone has owned and driven both in all seasons I would like to hear how they think they compare please.

18 minutes ago, Wino said:

On the old 9N Polo/Mk1 Fabia platform, there's a temperature sensor inside the control panel that has a tiny fan pulling cabin air over it. I assume this is to give a feedback mechanism so that when the desired cabin temperature is reached, the heater flap motor can be re-adjusted as required to maintain that.  

 

 

 

Correct, Climatic is self regulating but only a rough idea given by that sensor. No separate outlet temp sensors like Climatronic.

On 13/09/2019 at 16:36, Tech1e said:

 

Correct, Climatic is self regulating but only a rough idea given by that sensor. No separate outlet temp sensors like Climatronic.

 

So, to conclude: Climatic regulates the temperature by mixing the chilled air with heated air. In case the A/C is off, it mixes outside air with heated air, right?

How do one interpret the temperature gauge, as a rough idea of the desired cabin temperature? Any idea on what 9, 12 and 3 o'clock should represent?

1 hour ago, damjanev said:

So, to conclude: Climatic regulates the temperature by mixing the chilled air with heated air. In case the A/C is off, it mixes outside air with heated air, right?

 

It just varies the temp flap inside the heater box, thus exposing more or less of the heater matrix so, yes.

1 hour ago, damjanev said:

Any idea on what 9, 12 and 3 o'clock should represent?

At a guess - 9 o'clock = all outside air, 12 o'clock = 50:50 outside and heated air, 3 o'clock = all heated air.

 

Temperature depends on the outside air temperature and engine water temperature - so won't be a fixed value for a given setting of the dial.

I'm horrible at diagrams and drawing generally, but this is the system as I understand it. 

 

All of the incoming air first goes through the A/C evaporator shown on the left of the sketch, then it gets to the heater flap where it  is proportioned between a part that goes through the heater matrix, and a part that bypasses it. These parts can and will vary anywhere between 0 and 100%, depending on control dial position, and measured cabin temperature.

 

With heater flap driven to position A, none of the incoming air passes through the heater matrix. 

If it's driven to position B all of the incoming air passes through the heater matrix.

 

 

 

 

 

 

1 hour ago, PetrolDave said:

At a guess - 9 o'clock = all outside air, 12 o'clock = 50:50 outside and heated air, 3 o'clock = all heated air.

 

Temperature depends on the outside air temperature and engine water temperature - so won't be a fixed value for a given setting of the dial.

 

All outside air (or max a/c) would be about half past seven (full left) 😉 

 

 

1 hour ago, Tech1e said:

 

It just varies the temp flap inside the heater box, thus exposing more or less of the heater matrix so, yes.

 

I get that, but it was mentioned that there is a sensor that regulates the said flap, the one that @Wino illustrated (thank you), based on the gauge position.

So the question seems to open whether to interpret the gauge as a rough temperature setting (absolute setting e.g 25 degrees) or a rough temperature relative to outside temperature (e.g 5 degrees colder or 7 degrees warmer than outside)?

 

I can only suggest you get a thermometer and do some experimenting, but I doubt there's any accurate correspondence between the dial position and any specific temperature.

 

7 hours ago, Wino said:

I can only suggest you get a thermometer and do some experimenting, but I doubt there's any accurate correspondence between the dial position and any specific temperature.

 

I wonder if the results would be outside temperature dependent. 

I'm sure they would.

Why do you need to know the temperature? Can you not just adjust it until you're comfortable?

I thought that the climatic system was a step in between climatronic and full manual heating, when I had it in my mk5 golf and you set the knob to the middle which was 22 IIRC it blew warmer air in winter than it did in summer, i'm not sure if this was just relationship between the ambient outside air temp or a sensor in the cabin, but it seemed to be biased either towards heating or cooling.

 

Its mentioned on other forums but I haven't seen any official information on how it works 

Edited 16 September, 20196 yr by SuperbTWM

This sort of question was never asked when cars were simple and there werent temp controlled digital readout Climatronic systems, you use a bath or shower mixer tap without wanting to know the temperature.

 

One thing to add to the previous descriptions, the talk of the incoming air going over the cold evaporator and the being reheated, when warm air is selected the aircon pump will only be cycling a tiny amount of refrigerant and wont be cooling the evaporator.

5 minutes ago, J.R. said:

One thing to add to the previous descriptions, the talk of the incoming air going over the cold evaporator and the being reheated, when warm air is selected the aircon pump will only be cycling a tiny amount of refrigerant and wont be cooling the evaporator.

 

it will be, otherwise you wouldn't be getting the dehumidifying effect although obviously the colder (ambient) it is the air con compressor will have to work less hard to get the evap temp down.

Edited 16 September, 20196 yr by SuperbTWM

I have the VAG Climatronic self study guide but we are not talking climatronic here but a manual system, the only way t be sure is to check the evaporator temperature using measuring blocks in VCDS on both AUTO and ECON, pretty sure I have done this before and even on auto the evaporator only went down low enough to sustain the required interior temperature setting, you could also see the compressor load value drop off.

 

I will check it tomorrow as my next car has only a manual system I think (not seen it yet) it will be interesting to compare the two.

If the evap. did not get down lower than the ambient air travelling over it to condense the moisture in the air then the many millions of people that use it in the cooler months to clear their windscreens must be experiencing true witchcraft, just saying.

I will check it tomorrow if my memory does not let me down.

 

I'm sure it will be lower but not to the degree that was suggested, we will see.

Edited 16 September, 20196 yr by J.R.

Just out of interest @J.R., who do you think initially said the evaporator was always cooling, even with A/C off?

This line of yours - "the talk of the incoming air going over the cold evaporator "

Which talk?