I have a 2003 Mini Cooper. The A/C does work properly. But it starts blowing hot air after driving for 10 minutes, even if the A/C is not on. The hot air comes out from the two small air vents under the window shields. Could you please tell me if this is a serious problem with the cooling system?
I appreciate every reply.
Thank you.

 

Sounds like the refrigerant is low.

Do you have the manual or auto system?

 

When ypu say "cooling system" you are refering to the ac system right?
Might be low refregiant...could be a blend door stuck...or if auto ac could be the controller...
just need to start troubleshooting it...
Check the simple stuff first....like r134a (refergiant) level....and more than needed is actually WORSE than less...so just don't squirt a can in....the mini system uses less than 1 pound from empty to full....so it might be a couple of ounces low....

 

Thank you for your reply.

The AC is auto system. The hot air is from the vents of front window defroster even though both the AC and defroster are off.

 

Thank you for your reply. I will check the refregiant.

 

I find with the temp controler set to anything above "lo", even with the fan off, i get warm air from tge vents just from airflow...
To prevent getting any extra hear from tge vents (even fan off), the auto temp comtroler needs to be set to low....then you can shut it off the fans/controler.
If you still are getting warm air, one of the doors that blend the warm/cold air might be stuck.

 

After checking refrigerant level, I'd also try it in 'recirc' mode with the fan off. That should stop any airflow at all. After that, as Zippy said, it's just troubleshooting. Are you saying that even when it's hot out, the AC starts cold, then gets hot? Does it also blow hot out of the other vents, or are they cold?