foggy windscreen...

[broonski]

I just got back from a bit of a drive to tamworth (for the musc festival ;)) my fender was fine on the trip but after i got back i was driving down to the central coast (same day i got back) and as soon as i hit the freeway there was a smell of radiator coolant coming into the cab and the windscreen started fogging up. A quick roadside check revealed absolutely nothing, and a proper check over of my truck didn't tell me anything else about what might be the cause. My truck is a 300 tdi defender.
Can anyone help me out with some ideas as to what might be the cause?

cheers,
bryce

[weeds]

the heater box/radiator thingy....although when mine failed it leaked on the inside of the car

for one reason or another the expansion tank might have let out a little bit, overfull maybe