Herb, you definitely have a vacuum problem. The system has vacuum switches that keep various part from operating till the engine is running. The defrost position by passes this condition. Check the vacuum at the bottom of the servo (two lines; in and out of a water temp vac switch). The out is the vac source for the inside controls.
Be sure your plug is pushed onto the servo all the way.
Look under your battery for corrosion. The servo vacuum harness passes through there.