Hi, I'm in the UK. The outside temp is 17C and I've got the cabin temp set to 16C. By my reckoning, the air flowing into the cabin should be at 17C with the AC switched off. It starts off that way but the air vents start blowing warm air once the engine has warmed up so I then have switch on the AC. Does anyone else notice this? Is it a fault? If so, what's the likely cause?