After a week on the trail with the new SATV windshield I found that I was very glad I bought one that flips up because...the heat from the radiator flowing up and through the dash is unbearable with it closed. When you think about it, heat rises as it comes off the radiator and the push of air while moving or by the fan just pushes it over the upper edge and right into the cab. If the windshield is open, that pressure overcomes the flow from under the dash but if closed, airflow around it pulls a vacuum..or lowered pressure.. on the cab and really pulled in that hot air from the front.
I did find a fast and low tech cure though...and it works. Get yourself a piece of memory foam 4"x4"x5' long. Remove the hood and the storage compartment. It's just one 10mm bolt and a few screws. You will see where the air goes into the dash along the top. If you look to either side you will see the role bars so notch each end for those bars about 4"s in from the ends then work it in and around those bars and toward the center between the frame and plastics. On the drivers side you will see one of the control boxes that is mounded on top. Notch around that leaving at least 2"s of foam on the back side. On the passenger side there is one wire set that needs to be pushed down against the frame. Finish stuffing your foam in well enough to seal it all off and so the storage compartment will drop back in. That's it. Sealed. Now it can be removed in winter for some warm air if needed and reinstalled in summer.
While I was there I also used some duct tape and sealed up some small holes on the plastic firewall. I need to design and boot or shield for the gas peddle but that looks pretty easy too. For now this will do it. I also think this will keep a lot of extra dust out of the cad too...at least what's being tossed-up from the front wheels.
Take Note CFM. 10 cents worth of foam will help keep customers cooler and happier.