77 300D

I bought a 77 300 D. that was mechanically a basket case, but had a nice body and interior. I have fixed everything and I am down to the last thing on the list, that being the heater control servo. The PO has cut and plugged the heater hoses effectively disabling the heater. While a lot of heat is not necessary in Florida, with our high humidity, some would be nice to defrost the windows. I have looked at the servo made by Unwired ($700). It may be that it is the way to go, even though it is expensive, unless some of you knowlegable people know of a way to rig up a valve with some sort of a control mechanism to by pass that servo. But, I still am at a lost as to how you would get the vacuun to the vent pods. Any help would be greatly appreciated.