Help with frost on inside windshield

Your windshield cowl drains could be plugged with debris and/or frozen. Snow melts, cowl fills with water and leaks into the fresh air vent/blower housing.

 

So this may sound odd and strange, but fill a sock with cat litter and leave on dash next to windshield. Helps with that and fogging on the windshield.

 

Skip the cat litter (good idea @Choco_Taco , but there's an easier solution). Clean the inside of your windshield with isopropyl alcohol. I learned this trick when I worked for a local ice cream shop as a teenager. Alcohol freezes at a much lower temperature than water so it takes a lot more to frost over. We used to clean the inside of the freezer display cases with pure alcohol and they'd never fog up. Anything else like windex or glass cleaner which is water based will introduce water and create fog. The alcohol trick will help mitigate the fogging issue, but ultimately as others have mentioned, minimizing the water/moisture you introduce to the truck (snowy boots) will be your best bet.
I still use alcohol to clean the glass shelves in the fridge- impressed the mrs. when I showed her that one.

 

Doesnt our teucks have electronic switch for fresh air and recirculate? I have to push that when the truck is on and it turns off when truck is off. Once in the truck again I have to reengage the switch to recirc air. But I usually run fresh air anyways.

 

mine will do this and is normal with a wet mat
you need to turn the heat up, no recirc and fan on high to get moisture out

short trips wont help the issue

 

In the winter, always keep it on fresh air. Once warm, crack a window, to let out the moisture laden air, to help keep the inside dry. If you have wet carpet or mats, keep the fan on high, and regulate the temperature with the windows.