1999 ram van 3500. Windows fog during driving

Thank you! Where is the intake located for the cabin air? Could it be clogged? Van sat for some time, perhaps a nest inside? Cracking passenger windows helps, but we live in cold climate, not always possible.

Got good air flow or output from defroster vents? .. IF rodent nest were the problem.. Should have blower fan noise from debris in fan wheel and very low air flow from any mode selected... Proper air flow from defroster should blow a sheet of notebook paper OFF of the dash without any problem! .. With that said.. I'm out of ammo!

Decent flow from vents. Fog builds from outside edges and creeps into viewing area. Replacing fan motor today, as it does not always start until vehicle is warmed up. Suggestions?

IF new fan motor doesn't help or acts the same... Possible blower motor 'resistor' is failing... Good luck with it!

**update. I found the issue. While the blower fan was out I was able to locate the flapper that vents fresh air in through passenger fender. The actuator for the flapper door was frozen. I was able to open the door from the inside. Viola.

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