Anyone any ideas on this, driving along today, heavy rain outside, warm though 19 degrees, temp in car set to 16 but no air conditioning on, fan speed 1, air circulation set to bottom , mid and screen, then suddenly, what you can only describe as a type of fog comes from the center vents just for a few seconds, car coolant temperature normal, all normal again, as I said just did it for a few seconds,

 

It's normal for any car to have this happen. This is the colder less moist A/C air coming into contact with warm, more moist air.

 

Ok thanks A/C wasn’t on at the time

 

I'm having visions of the opening sequence of "The Prisoner." Hopefully you don't wake up in The Village.

 

It's usually the same thing, colder air mixing with warmer moist air. It creates a little fog. It can go the other way around where blowing warm air meets outside cooler air. It creates little fog that is not "smoke". You commonly see this from exhausts on cars where it's cool mornings with warm exhaust temps.

 

Were you driving really fast?

 

Your Jaguar just farted...

 

More seriously, you said that the air direction included the setting to 'screen' (defrost).

Many cars run the air conditioner in that setting to defog the windows (and it WAS raining/humid).

Sounds to me as if the A/C was just cycling on and off.

 

I agree with Carbuff 2. Had this happen on an airliner a few weeks back. Fog was just flowing out of the vents when we landed, looked like we were setting up for a Halloween movie. Really spooky. Warm moist air + cold heat exchanger = fog. Nothing to worry about but you should take a picture because it looks cool (no pun intended).