George, You did not say which heater you have. The connection described by Bartamos is correct for any heater.. Here is a page from the Chevy Accessories Handbook showing the heater GM sold from 1934-1946. Yes, there were a lot of different heaters used but this is the Harrison from GM. They also sold the defroster (which needs a separate switch) that mated to the heater. Photo attached. A photo of the Heater and Defroster switch is also attached. Harold
