If you can see the vents moving when pushing the buttons, and hear the servo running, I would almost say the rest of the system is working. If I'm reading the schematic I have correctly, the defrost system has a seperate relay that runs full voltage to the motor and bypasses the blower resistors. Otherwise power runs through a series resistor block, where the voltage is controlled by the servo unit. Looks like the servo has a switching device that connects or bypasses the resistors to control blower speed. Before power reaches the blower and after the resistors, it goes through a master vacuum operated switch with a green vacuum line. I would check to make sure you have power to the resistors, power out of the resistors, and to make sure power is getting through the master vacuum switch. If you have power to the resistors but none out, then you either have a bad connection, bad resistors, or a bad servo. Looks like there are total of 6 connections at the resistors, one being power in, one power out, and a tap between each of the 5 resistors in series (which connects to the servo), so you can unhook it and check for continuity and resistance in the block. Could also be as simple as a broken vacuum line to the switch, which is the very first thing I would check.

Also, when in heat mode, the blower will not operate until the engine water temperature reaches a certain level (except in defrost).

I believe the resistors are in the blower motor compartment under the hood at the rear under a plastic cover. The vacuum switch should be behind the glove box.

As for the compressor not running, I would check the Freon level before assuming something is wrong. It may simply be too low to activate the Freon pressure switch. Or maybe the pressure switch is bad. I would think the fan should run though with the dial set all the way to cold and in Auto mode. The compressor circuit also have some vacuum switches and misc as well.

Maybe this will give you a path to diagnose the problem.