Aircon Auto-Mode causes external air intake

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

aneesh84
Posts: 323
Joined: 31 Jul 2011, 22:29
x 13

Aircon Auto-Mode causes external air intake

Post by aneesh84 »

Whenever I run my C5 AC on Auto Mode, it is taking external air into the cabin. Which means all the road pollutants and smoke from other cars are sucked inside making the Auto Mode unusable. Is this how its supposed to be? I would have found it more logical for Auto mode to engage cabin internal air circulation.

User avatar
GiveMeABreak
Forum Admin Team
Posts: 24442
Joined: 15 Sep 2015, 19:38
x 2671

Re: Aircon Auto-Mode causes external air intake

Post by GiveMeABreak »

No that wouldn't work and you'd probably die from carbon dioxide poisoning from the passengers if it was designed that way (if you've ever seen the Apollo 13 film - you'll know the problem they had).

The system is designed to allow partial or full air recycling depending on the outside temperature, the inside temperature and the temperature requested by the passengers. The system will cut off this function if there is a risk of misting (via the hygrometry sensor).

There is a pollution sensor to detect Nitric Oxide or Carbon Monoxide from the exterior and this will determine the level of air recirculation. Bear in mind this does nothing for the smell of the pollutants - but it can inhibit exterior air intake to the cabin if it detects high levels of pollutants.

Om my C5 X7, the system often switched to internal air only whenever I hit reverse to prevent the exhaust fumes from being sucked up into the cabin as I reversed, so yes, the system is designed to work like that for good reason.