[ryangus]

Had to use the demister for the first time this evening in cold, wet weather.  Despite the climate control being set to 24 degrees, the air coming out of the demister was unpleasantly cold.  Why can't the demister use warm, dry air from the AC?

[The Gonz]

News to me. I thought it did, or at least it should when normal engine temperature is reached to warm the air and a healthy charge of refrigerant in the AC to dry it.

[FatBoy]

The only reason that I can think of is that the engine wasn't up to operating temperature, so no warm air was available.   

[Dazzler]

Had to use the demister for the first time this evening in cold, wet weather.  Despite the climate control being set to 24 degrees, the air coming out of the demister was unpleasantly cold.  Why can't the demister use warm, dry air from the AC?

By nature diesel motors are slower to warm up (thicker block and generally lower revving)

[ryangus]

Nah, this was after an hour of driving.  Thought it very strange that it was cool compared to the warm air that was pumping into the footwells.

[PhireSideZA]

Nah, this was after an hour of driving.  Thought it very strange that it was cool compared to the warm air that was pumping into the footwells.

Cold AC air diverted to the windscreen to remove the mist/moisture along with warmer climate controlled air blowing towards the footwells? It could be that when you select the front demister, this scenario happens. I find with my car if I turn the front demister off and the dashboard vents reopen I will get a blast of cool air followed by the air at the temperature set on my CC display. So perhaps it is normal unless I am understanding your post wrong?

[Phil №❶]

I'll check ours next time, but to dehumidify the screen, the air can be warm as well, so I hope that is the scenario. Rolls Royce air conditioning systems actually purposely freeze the air and then re humidify it to the selected temp to cater for all international sales and no mist on the screens either. We can't have our ladyfolk having dry skin, can we. Yer gets what yer pay for, I guess.