I've had the car for about 6 weeks.
There was one time where the windscreen fogged up so I directed the air to the windscreen and it cleared (from memory).
Other than that one instance I haven't really checked, so I am not ruling out it was faulty when I got the car.
I noticed the vacuum hose connection at the rear of the engine (shown below) was very loose and was not air tight. I made the connection air tight last night by sealing the joint with amalgamating tape but it did not fix the issue.