I need the wiring diagram for the limit switches

There should be a diagram on the furnace someplace if not look up your local Intertherm distributer

The furnace is operated by a control circuit which typically begins from the power supply or control voltage transformer.

220 Volt Electric Furnace Wiring | Electrical Wiring Illustrated (http://www.ask-the-electrician.com/220-volt-electric-furnace-wiring/)

This should help.