Crew cab truck. Exterior ambient temperature is -22. Interior temperature approximately +20 and rising; defrost setting, fan speed is set to high, high heat to defrost windshield and warm up truck. Idle time of 10 minutes or less. Truck coolant temperature approximately 135 and climbing. All snow and other materials cleared from exterior of truck. Little to no moisture on interior of vehicle. While driving at speeds greater than 15mph while first starting out (within 20 minutes of starting vehicle) and changing elevations greater than 15 feet (rolling hills); expect to see a sudden build up of frost on the interior of the windshield causing complete loss of visibility. I have had to carry a scraper and be actively scraping the windshield to be able to see enough to get to the side of the road and wait for the windshield to clear itself. Have almost put vehicle into ditch once due to brushing snow bank with tires after first occurrence. Issue also occurs if windows are rolled down to help displace any possible moisture. Issue has occurred on several occasions and it has been reported to the local dealer and Dodge Ram corporation. Have talked with several other Dodge Ram owners and all are reporting similar situations. Dealer has been notified of this issue on multiple occasions by multiple people and they are stumped as to how to repair / resolve this issue. Claim it to be environmental and out of their control. Personally believe defrost system is not of proper size / configuration to prevent issue from occurring.

- Fairbanks, AK, USA