Yes, you can run the A/C and heat at the same time. Should be handy on a humid or rainy day when you need to clear the windshield and take some humnidity out of the interior. They are switched separately and the heater/defroster uses the cowl intake door to give you the choice of either fresh air intake or recirculated air. All very versatile, but more different switches and levers in different places than on your modern ride. Cheers, Roger '54, '55, '56, etc.