Octavia III A/C Compressor

[SkodaMies]

As we all know, all new VAG cars have this annoying feature which turns the a/c compressor off when outside temperature drops below the temperature what is been set inside the car, no matter what you do. For example if outside temperature is 25C (77F) and inside the car is 20C (68F), everything is fine. But if you drive long enough and outside temperature drops to 17C( 62,6F), car will became like a steam sauna. Still 20C (68F) inside but the incoming air is very humid, causing steamy windows and wet back. Workaround to that is to push the defrost button which engage the compressor to run approximetly three more minutes.

VAG is trying to save the earth with this feature, because in their opinion there's no need to warm the air and then cool it down again. They say it's just a waste of energy.

Is there anyway to prevent this feature with VCDS?

[rwbaldwin]

The first thing to check is the evaporator drain is not blocked. If the air is very humid then this could be the cause.

[SkodaMies]

Evaporator drain is not blocked. Problem is when outside temperature drops, air comes more humid. Then this humid air is blown inside the car through a moist evaporator. You can test what will happen when you shut off your a/c when outside air is very humid and little colder than the temperature that has been set in the car.

VAG says "Once the desired temperature is reached, the climate control system will not continue to dehumidify the interior."

[rwbaldwin]

Evaporator drain is not blocked. Problem is when outside temperature drops, air comes more humid. Then this humid air is blown inside the car through a moist evaporator. You can test what will happen when you shut off your a/c when outside air is very humid and little colder than the temperature that has been set in the car.

VAG says "Once the desired temperature is reached, the climate control system will not continue to dehumidify the interior."

It's not a dehumidifier. I don't see the misting up problem you are having. I drove one on Thursday, in stop and go traffic, I ended up in the shade under a flyover. Despite it being humid and the cooling going off, it didn't mist up all the windows. For that to happen, the windows would need to be cooler than the incoming air.

To answer your original question, AFAIK, you can't program an overlap between heating and cooling.

[SkodaMies]

If it's not also a dehumidifier, why on earth there's a humidity sensor inside my car? Is there another magic way to dehumidify the air inside the car? I know this is not a problem for most of the people, but I have to drive this thing often in these conditions. I know a lot of Octavia III owners and they all suffer from this same thing. I had Superb II beofre this one and it kept the compressor running until the temperature dropped near 5C (41F). Infact all the cars I have had before this one overlapped between heating and cooling.

Edited 26 July, 2014 by SkodaMies

[andyvee]

It would have kept the compressor running, but at about 5% if there was no requirement for cooling the air.

 

There is an adaptation somewhere for the sensitivity of the humidity sensor - can't remember if it is on the Climate Control or the BCM though.

 

You are leaving the climate on AUTO aren't you as I can't say I have experienced any issues with msting up at all in the O3.

[SkodaMies]

Actually the compressor shuts down completly if there's no need for cooling or dehumidifying. And it does that no matter if you're on auto or manual mode. But I finally found the solution. There is an adaptation for compressor Co2 reduction, but for some reason you can't change the value. So you have to do it by coding. Module 8, byte 13, there's a value 10 (CO2 Compressor Activation Reduction activated). I changed that to 0 and now the air conditioning is working as it should be. Overlapping between heating and cooling

http://youtu.be/XN9SNqOidmI

Edited 23 August, 2014 by SkodaMies

[andyvee]

I thought it always kept the gas moving at a very low pressure to lubricate the seals, as per the O2. How have you determined it shuts down completely?

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[gadgetman]

If you keep the auto function on you shouldn't be seeing this.

[SkodaMies]

If you keep the auto function on you shouldn't be seeing this.

Shouldn't been seeing what?

[gadgetman]

Shouldn't been seeing what?

The misting issue

[SkodaMies]

But unfortunetly it's there. It's more like humidity issue than misting one. New Mercedes cars have this "feature" also. German engineers are doing strange things in pursuit of lower CO2 emissions.

[gadgetman]

But are you using auto?

[SkodaMies]

No matter which mode is used, it's same with auto and manual mode.

But not anymore

EDIT: when I say Auto mode, I mean Auto with A/C button pressed. I don't have any idea how it behaves only in auto without a/c button pressed.

Edited 24 August, 2014 by SkodaMies

[gadgetman]

Auto will activate the compressor as required.

Using a or setting a manual fan speed will run the temp as you have set continually and the compressor will behave as you have found. Ie it will shut off when you really need it on to prevent misting

[andyvee]

That's new then!

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[SkodaMies]

No it's not new. It is false It is as I said. No matter if it's Auto or Manual, dehumidifying stops (compressor shuts down) if there is no need for cooling.

[andyvee]

New as in on the O3, pretty sure the O2 didnt behave like this. I'll take a look at the measuring blocks for the compressor at some point.

[SkodaMies]

Only some of VAG cars have this feature. This is from site http://www.volkswagen.co.uk/technology/comfort-and-convenience/air-conditioning-and-climate-control

" Environmentally friendly - no CFCs

All air conditioning systems in our cars are environmentally friendly and do not use refrigerants containing CFCs. Some, such as the one in the Golf, feature an externally regulated compressor with an evaporator temperature which can be regulated between 2 and 12 C. This ensures the air is not dehumidified any more than is necessary, reducing the amount of energy required, and therefore fuel consumption."

Sad thing is that dehumidifying any more than necessary, is not enough.

[Kenny R]

Also quoted from your link...

 

"If the outside temperature is above 0?C, the cooling system cuts in as well to dry the air before it is heated."

[SkodaMies]

Guess that's the "old" version without the externally regulated compressor...

[Kenny R]

Since it also mentions the humidity sensor, and the externally regulated compressor and is dated 2014 it suggests that it is the latest version.

[gadgetman]

Do you have any official source for this claim?

[SkodaMies]

Here's a video. Outside temp 15.5C inside 20C, Climatronic Auto position and compressor is off.

http://youtu.be/qkv5VQDj3Tc

[SkodaMies]

Since it also mentions the humidity sensor, and the externally regulated compressor and is dated 2014 it suggests that it is the latest version.

There are at least two different versions of Climatronics and how it operates because it says Some, such as the one in the Golf...