General A/C questions - missing some components

What do you have for a manual? The factory shop manual should picture the temp switch

The expansion valve is the entire key to how and why AC works. It is the "restriction" that causes refrigerant to evaporate. WIthout it, all that would happen is that refrigerant would go round and round in the system.

The problem is, nobody seems to have a 73 manual, so I don't know the differences between a 72 and 74.