Cold weather doesn't effect mine, damp wet weather does. I've been caught out in heavy fog, and the windshield was as foggy inside as it was out side, I had a towel to keep it clear. The heater mounted under the seat blowing out on the floor board didn't effect the fog, just got my feet hot! My Vintage Air Mini, has outlets for defrost, but no way of getting the air to the glass without cutting holes, I opted not to cut the dash. I don't drive the truck enough to use defrost, maybe in the last 20 years I needed it three or four times.
