Recently I was driving with my air con on (not in auto mode) at 20 degrees setting and after a few minutes it switched to recirculate buy its own. It happened on two separate occasions after I started driving. - anyone know what might be causing this? Expensive fix?

 

Clack, this can be caused by 1 of 2 things as I can see it. The first (being the more likely culprit) is the fact that the button has gotten sticky over the years and is not backing off completely. So, with a good bump, the switch makes contact and the A/C system thinks you pushed the button. The other potential is that the lock in circuit is failing and that is causing the recirc to lock in. Not as likely. I would say that you can try spraying some contact cleaner on the recirc button and then while wet, push the button a number of times (20-30 times). That will help clean the contacts and also help push any garbage out of the way of the button. If things continue, then you are looking at something more physical and will not be correctable. Either way, I think you would be looking at replacing the A/C module or the radio module (depending on whether you have the Nav system or not).

 

You don't give any of the prevailing conditions when this happened, but a large temperature difference between the set temperature and the actual cabin temp will, by design, cause the recirc flap to close automatically. Also, if the cabin sensor is maybe fluffed up or its fan is not running that could confuse the control module. So before splashing the cash on any replacement parts, just check that sensor behind the little square grill is clean and its fan is running and that the external temp sensor is accurate (Fitted in the lower air inlet at the front of the car)