Hi all.

I have a little problem with my car.
I left it idling on the drive because I have a problem with not getting any hot air out the vents.
It was idling for about 10-15 mins, the cooling fan kicked in eventually as the temperature rose, it never hit the red.
Then after I turned off the engine, the expansion tank was hissing, steam was coming out of it (I also have a new cap on it) and the water level rose about 15mm above the maximum level.

Car is a mk4 fiesta, 1.25.

Any ideas on what the problem could be?

Cheers, Jason