Where do I start on my 71 Plymouth Fury to get the heat and A/C working?

check the fuse for it first then check the blower motor on it,chances are on that old of a car you may need a new blower motor switch or just have a blown fuse,the climate control also will have an affect on the blower motor if it isn't working right,id start with the fuse first though,then run12 volts to the blower motor to make sure its working then go from there with it,i own a 73 that i bought for parts,good luck.