What was evil about all Corvairs was that the heat came from the rear of the car forward, and from below. You were okay-ish if you had bucket seats, because then you could keep you hands warm from the heat coming from the rear seat heater outlet at the floor, and because the heat for the front went under the floor, you might have icicles on your eyebrows but your feet might be unfrozen. Trying to keep the de-iced portion of the windshield larger than 2 half moons about 4-5 inches in radius, meant closing off the only real source of heat, the rear seat heater outlet, and running everything through the defroster vents. I tuned the thermostatic vents, sealed them up tight with silicone to get rid of airleaks, and managed to survive...just. Mind you, Corvairs more than made up for their failings as heated vehicles, by being the worlds' best ever snow vehicle..ever. I got through unplowed highways with 30-36 inches of new snow in my Corvairs. I remember tying a rimless tire over the front bumper and pushing a stuck police cruiser up a hill with it...Every SUV I've been in since doesn't even come close--some of the Range Rovers, perhaps..