Adjusting the air flow

[Caldwell_]

My car's AC always blows air to my feet when I set it to automatic. I want it to blow to my feet and windshield. Can I change that? Also, does the automatic setting help prevent fogging?

 

[PHEV07]

My car's AC always blows air to my feet when I set it to automatic. I want it to blow to my feet and windshield. Can I change that? Also, does the automatic setting help prevent fogging?

Hello Caldwell

Welcome to our Forum.

What Year is your vehicle.

For the 2018, 2022 and 2024, do not use Auto, but rather Press the Mode repeatedly untill you come to position for Windshield and Floor airflow the press Fan button to increase the Fan Speed.

Not sure about earlier Models

 

[greendwarf]

My car's AC always blows air to my feet when I set it to automatic. I want it to blow to my feet and windshield. Can I change that? Also, does the automatic setting help prevent fogging?

As already answered regarding the Mode (same for all years) and yes the A/C will demist the screen but remember once switched off it just dumps the moisture back again - oh, and the PHEV seems to suffer from excess internal condensation anyway, although I've never worked out why!

 

[littlescrote]

As already answered regarding the Mode (same for all years) and yes the A/C will demist the screen but remember once switched off it just dumps the moisture back again - oh, and the PHEV seems to suffer from excess internal condensation anyway, although I've never worked out why!

It doesn't dump all of the moisture back to the windscreen, only that left condensed on the evaporator. Much more will have been condensed and drained away.

The trick is to use recirc so that all mpistyure gets removed from the cabin air, rather than try to continually dry outside air that is saturated. And when you stop, switch the mode to feet to close the path of the moist air away from the windscreen.

 

[greendwarf]

It doesn't dump all of the moisture back to the windscreen, only that left condensed on the evaporator. Much more will have been condensed and drained away.

The trick is to use recirc so that all mpistyure gets removed from the cabin air, rather than try to continually dry outside air that is saturated. And when you stop, switch the mode to feet to close the path of the moist air away from the windscreen.

Actually that is not the recommended method of getting rid of inside condensation, which is normally due to passengers breathing it out. You need to have the recirculation off and draw in drier outside air as a replacement - especially in Winter. The only time you would use the above method is in warm humid conditions, which is not normally a problem in the UK.

 

[littlescrote]

I was only an automotive HVAC engineer testing for global manufacturers in a climatic controlled wind tunnel for 12 years, what do I know about it?

You make your choices based on which has the highest relative humidity. When it's wet outside, warm or cold, I think you'll find it's outside. Inside may well start high, but on recirc it will come down continuously, whereas outside air will always stay high.

 

[JonathanCarmichael]

Ah, so you mean the solution depends on what your problem is...

 

[greendwarf]

I was only an automotive HVAC engineer testing for global manufacturers in a climatic controlled wind tunnel for 12 years, what do I know about it?

You make your choices based on which has the highest relative humidity. When it's wet outside, warm or cold, I think you'll find it's outside. Inside may well start high, but on recirc it will come down continuously, whereas outside air will always stay high.

In which case you will know that condensation is caused by a temperature difference between the air containing the moisture and the surface it is deposited on and nothing to do with the internal and external humidity difference!

 

[littlescrote]

Of course it's caused by that, but the point is that if you've used recirc and have reduced the moisture in the air, there is nothing to condense on the cold surface, whereas if you are bringing in outside air and have only partially dehumidified it, there will still be plenty of moisture to condense.

 

[greendwarf]

Of course it's caused by that, but the point is that if you've used recirc and have reduced the moisture in the air, there is nothing to condense on the cold surface, whereas if you are bringing in outside air and have only partially dehumidified it, there will still be plenty of moisture to condense.

Which is why the screen demist button turns on the aircon automatically but if it is just the temperature difference causing the condensation, drawing in outside air, rather than recirculation, will normally speed up the process.

As an aside, I sometimes get the reverse problem in summer when using the aircon on entry the Rotherhithe tunnel when the colder screen hits the moist air inside and I get condensation on the outside! Took me a while the first time to realise why the aircon wasn't clearing the screen!