Dash A/C blows out of defrost when climbing or head wind

keefr wrote:
Anyone remember the old vacuum-operated windshield wipers that stopped going uphill and flapped like crazy coming down?

Yep... We used to make our own vacuum reservoirs from large juice cans. Back when the cans were actually made from tin that we could solder homemade fittings to. That made a big difference unless it was a really long uphill climb.